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THE HYDROLYSIS OF AM MONIUM
ACETATE AND THE IONIZATION
OF WATER AT 2.18° AND 306°
BY
ROBERT BROWNING SOSMAN
sº
A THESIS
SUBMITTED TO THE FACULTY
*OF THE
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
IN PARTIAL FULFILMENT OF THE
REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
JUNE, 1907
s

Ql.
444
3%
Tu
J 1.
2.
NH- 3.
9) & 4.
5.
6.
7.
8,
9.
10.
11.
12.
13.
* CONTENTS.
PAGE.
Outline of the investigation . . . . . . . . . . . 5
Apparatus and procedure . e e s tº e º e e g g g c & © 5
Instrumental errors and their correction . . . . . . . . . . . . 8
Preparation of the substances and solutions . . . . . . . . . . . 9
Errors affecting the solutions and their correction . . . . . . . . 13
The specific-volume data . . . . . . . . . . . . . . . . . . . . 21
Conductance-capacity of the apparatus . . . . . . . . . . . . . 22
The conductivity data . . . . . . . . . . . . . . . . 24
Equivalent-conductance values at round temperatures . . . . . 32
Final values of the equivalent conductance and their variation
with the concentration and temperature . . . . . . . . . 36
Ionization-values and their variation with the concentration and
temperature . . . . . . . . . . . . . . . . . . . . . . . . 39
Hydrolysis of ammonium acetate and ionization of water at 218°
and 306° . . . . . . . . . . . . . . . . . . . . . . . . . 41
Summary . . . . . . . . e e º ºs e º 'º º a tº s ºn e º e e º B & 46
THE HYDROLYSIS OF AMMONIUM ACETATE AND THE IONIZATION
OF WATER AT 2.18° AND 306°.
1. OUTLINE OF THE INVESTIGATION.
This investigation is substantially an extension to higher temperatures
of the investigation of Noyes and Kato (see Part VI)* on the hydrolysis
of ammonium acetate and the ionization of water at 100° and 156°.
Noyes and Cooper (see Part V) have, to be sure, determined roughly
the ionization of water at 218° from the hydrolysis of sodium acetate;
but, on account of the small degree of hydrolysis, the probable error in
their calculation is large. It was the object, therefore, of the present
investigation to derive as accurately as possible the value of the ioniza-
tion of water at 218° and at 306° from the hydrolysis of ammonium
acetate. The experimental data necessary are: the conductivities at 218"
and 306°, at small concentrations, of sodium chloride, sodium acetate,
hydrochloric acid, sodium hydroxide, and ammonium chloride; the con-
ductivities of ammonium hydroxide and acetic acid at varying concen-
trations; and the conductivity of ammonium acetate alone and with vary-
ing additions of ammonium hydroxide or acetic acid. Of these, the
data at 218° for the first three substances and for acetic acid have been
determined by Noyes and Cooper; those for sodium hydroxide at 218°,
by Noyes and Kato; those for sodium chloride at 306°, by Noyes,
Coolidge, and Melcher; and those for hydrochloric acid at 306°, by G. W.
Eastman. The data for sodium hydroxide at 306° have not yet been
determined, but an estimate of its equivalent conductance for complete
ionization has been made on the basis of the results at lower temperatures
and the relations to the conductance of the other substances.
This investigation, together with those referred to above, was made at
the Research Laboratory of Physical Chemistry of the Massachusetts
Institute of Technology.
2. APPARATUS AND PROCEDURE.
The apparatus employed was in principle the same as that used in
the previous high-temperature investigations. The conductivity cell or
bomb, the details of which have been fully described in Part II, was a new
*These references are to the Parts, sections, and tables of Publication No. 63,
of the Carnegie Institution, by Arthur A. Noyes and others, of which publication
this article formed Part VII.
5
6 The Hydrolysis of Ammonium Acetate, Etc.
one (No. 4) made in June, 1904.” An open cylindrical platinum-iridium
electrode was used as in the work of Noyes and Kato.
For the purpose of merely testing solutions at 18", when it was not
desired to make a measurement at higher temperatures, a small glass
conductivity-cell was used, such as is represented in figure 19, Part IX.
This had a capacity of about 40 c.cm., and was in the form of an ordinary
pipette; the upper tube was provided with a stopcock, the platinum elec-
trodes were sealed in vertically through the shoulder of the bulb on
opposite sides of the upper tube, connection being made through glass
tubes containing mercury, and the lower exit tube was turned upwards, so
as to rise above the liquid in the temperature bath. Solutions could be
forced into this cell without any danger of contamination from the air.
The resistance of the solution in the bomb was measured by means
of the usual arrangement, consisting of a new Kohlrausch three-meter
cylindrical slide-wire bridge (Hartmann and Braun No. 283), a small
induction coil, and a telephone connected between the ends of the slide-
wire. A switch was arranged to commutate the current from the coil,
and another to connect the bridge with the lower or the upper electrode.
The leads were of heavy copper wire, connecting with the bridge or with
the leads coming out of the temperature bath by means of double flexible
lampcord and flat binding-screws.
The rotating carriage in which the bomb was mounted, as well as the
larger temperature baths required by this rotating arrangement, were simi-
lar to those used by Noyes and Melcher (section 28, Part III). Xyene was
used in the 18” bath, and naphthalene in the 218° vapor bath. A Beck-
mann thermometer was used in each. In the 306° bath benzophenone was
employed. Diphenylamine, boiling at 302°, was used at first, and some
of the data on ammonium hydroxide were obtained at this temperature;
but after a few experiments much of the substance had decomposed, and
the boiling-point rose and became uncertain. It was found impracticable
to use a Beckmann thermometer at this temperature, because its readings
were variable and not reproducible. A 0–360° Alvergniat thermometer,
graduated in degrees, was therefore employed.
*This bomb was used until June 5, 1906, when the lining of it cracked; after this
date another bomb (No. 3) was employed. The first trouble from leakage occurred
in February, 1905, after the bomb had been in use for one month, when the lower
lining cracked near the bottom; this was repaired by removing the lining and flow-
ing gold over the crack. No more difficulty was experienced, except from occasional
accidental leakage at the electrodes or the valve, until after the first heating to 302°,
when a slow leak developed through a tear in the lining of the upper chamber,
caused probably by unequal expansion of the steel and the platinum lining. The
leak was so slow at first, however, that the conductivity of the ammonium hydroxide
solution could be determined at a given time, and the bomb then removed and
cooled without further loss, the solution from the bomb being always analyzed after
each heating, whether there had been leakage or not. After some attempts to locate
and repair this leak, the upper lining was removed and a new one put in (March,
1906). The bomb then held until June 5, when the lower lining again cracked.
ſº
* * * : Section 2–Apparatus and Procedure. 7
...: ; ; ; ; ;
l: +. prevent contamination of the solutions by carbon dioxide or other
gases in the air, they were kept in closed bottles, and blown out through
an exit tube by means of compressed air which was purified by passing
through a train of bulbs containing sulphuric acid and potassium hydrox-
ide solutions. In filling the bomb, a procedure similar to that of Noyes
and Kato was followed; and the results show that appreciable con-
tamination by carbon dioxide was excluded. After the bomb was closed,
the air was exhausted by means of a water-jet pump or a mechani-
cal vacuum pump (see also pages 15–17). The residual pressure was read
on a mercury vacuum-gage.
The bomb in its carriage was then placed in the 18° bath and rotated
until the resistance became constant, after which nine readings were taken,
three on each of three known resistances, such as 101, 110, and 1,000
ohms. The 218° bath had meanwhile been heated and the naphthalene
brought to boiling. The vapor was temporarily condensed by the air
cooling-coil, the bomb and carriage introduced, and the naphthalene again
boiled until the Beckmann thermometer showed a constant temperature
nearly equal to the boiling-point of pure naphthalene at the prevailing
atmospheric pressure. At the same time the resistance of the upper
electrode was measured, showing how full the bomb had become and
also showing whether any leakage was taking place. After the nine
readings of resistance were made at 218", the vapor was condensed, and
the bomb removed and cooled to room temperature before a fan. The
measurement at 18° was then repeated to find out whether any change had
occurred in the solution. The same procedure was followed at 306°,
except that, in order to avoid loss of benzophenone, the bath was not
heated before introducing the bomb. The experiments at 306° were all
made after the work at 218" had been completed.
The temperature in the 18° bath was kept constant within 0.01°, and
was measured with a Beckmann thermometer. This was compared at
various points in the neighborhood of 18° with a Baudin thermometer
(No. 15958) which had been standardized by the Bureau of Standards at
Washington. The corrected temperatures of the standard are referred
to the hydrogen thermometer. At 218° the difference in temperature
between the vapor-bath and a calibrating bath containing pure naphthalene
was determined by means of a Beckmann thermometer.
The naphthalene used in the calibrating bath was obtained by recrys-
tallizing the purest Kahlbaum preparation once from absolute alcohol;
that the original substance is pure is shown by the fact that the recrys-
tallized material did not differ more than 0.01° from the original in
boiling-point. The 218 point on the Beckmann thermometer was deter-
mined in the calibrating bath after every second heating by reference
8 The Hydrolysis of Ammonium Acetate, Etc.
to the known boiling point of naphthalene under the corrected atmos-
pheric pressure as determined by a mercurial barometer. The 306° point
on the Alvergniat thermometer was frequently determined by heating it
in a calibrating bath containing pure benzophenone, prepared by crystal-
lizing a Kahlbaum preparation from absolute alcohol. For the boiling-
points of both naphthalene and benzophenone the values on the hydrogen
thermometer determined by Jaquerod and Wassmer* were employed.
3. INSTRUMENTAL ERRORS AND THEIR CORRECTION.
There was no appreciable inaccuracy in the temperature measurement
at 18°; and at 218° and 306° the measurement certainly gave the true
temperature of the bomb within 0.2°. An uncertainty of 0.1° in tempera-
ture at 218° corresponds in the worst case to less than 0.1 per cent in the
conductance, as the temperature-coefficient at this point is always less than
1 per cent. At 306°, 0.1° corresponds at the maximum to about 0.3 per
cent. No variation was, however, noticeable in the conductance after it
had reached its final value, so that the error, if any, is probably all in the
temperature value.
The slide-wire was calibrated three times by the method of Strouhal
and Barus: once by division into ten parts, and twice by division into
twenty parts. The results agreed within 0.1 mm., and the correction was
at no point greater than 0.2 mm. The 1, 10, and 100 ohm coils of the
rheostat were compared, on a Carey-Foster bridge, with the Reichsanstalt
standards in the Electrical Department of this Institute of Technology.
The 1,000 and 10,000 ohm coils were tested by making up a Wheatstone
system, using two standards as ratio arms and a third as known resist-
ance, adjustment being made on the slide-wire of the Carey-Foster bridge.
The maximum error found was 0.15 per cent, in the 1-ohm coil.
The measured resistance includes the resistance of the leads from the
bridge to the bomb. This was measured by the drop-of-potential method,
the bomb being placed in position as usual, except that the lower electrode
tag was wired tightly against a polished spot on the bomb itself. To the
resistance thus measured must be added, first the increase due to the heat-
ing of the leads inside of the bath, which was calculated from the size
and temperature-coefficient of the copper wire, and second, the resistance
of the stem of the electrode. The latter is, however, only 0.002 ohm. The
maximum lead resistance was 0.034 ohm, at 306°, while the lowest total
resistance measured was 19 ohms. The only possibility of variation in the
lead resistance was at the removable contacts between electrode tag and
electrode, bomb and carriage, carriage and supports, and the outside flexi-
*J. chim. phys., 2, 52 (1904).
Section. 3.-Instrumental Errors and Corrections. 9
ble leads and the main leads. All of these surfaces were polished with
fine sandpaper before each heating. Special experiments showed that the
brass contact surfaces are almost unaffected by tarnishing, but that the
steel surface resistances are increased appreciably by a film of oxide; also
that the variation in resistance at the sliding contact of the carriage on its
supports is inappreciable.
The current used in the measurements was made as small as possible,
so as to avoid the ejection from the electrode of adsorbed material. This
was accomplished by using the smallest possible voltage on the coil, after
weakening its spring by filing partly through it. Any error from polari-
zation caused by asymmetry of the coil, was eliminated by commutating
the current and taking the mean of the two readings.
The excess of pressure due to air in the bomb was only a small fraction
of the total pressure; for instance, if the air is evacuated before the heat-
ing down to a pressure of 2 cm. of mercury, and the vapor-space at 218°
is 2 c.cm., then the air pressure at 218° is 0.5 atmosphere, while the vapor-
pressure is about 22 atmospheres. With 2 c.cm. vapor-space at 306°, the
air pressure is about 1 atmosphere, while the vapor-pressure is about 97
atmospheres.* Hence the variation in conductivity due to the residual
air pressure is probably negligible.
Down to the lowest level ordinarily used, namely with the bomb three-
quarters full, the height of the solution in the bomb has no effect on the
conductance-capacity. In the experiments for determining the vaporiza-
tion-correction at 306°, however, the bomb was only half full at 18°; the
effect on the conductance-capacity was determined by filling the bomb only
to this level with a standard potassium chloride solution. The results are
given on page 23. The correction for the variation in conductance-
capacity with the temperature was made as described in section 36,
Part IV. *
4. PREPARATION OF THE SUBSTANCES AND SOLUTIONS.
The weights used in weighing out the solid substances and solutions
were all standardized in terms of the one-gram weight as standard. All
weights were reduced to weights in a vacuum before being used in cal-
culations. The atomic weights used were those reported by the Interna-
tional Committee in 1904, referred to oxygen as 16.00.
All solutions both strong and dilute, except those used for determining
the conductance-capacities of the apparatus, were made up, analyzed, or
titrated wholly by weight; the results are therefore independent of tem-
perature, and are expressed in terms of milli-equivalents per kilogram of
*Batelli, Landolt-Börnstein-Meyerhoffer Tabellen, p. 122 (1905).
IO . The Hydrolysis of Ammonium Acetate, Etc.
solution. All of the dilute solutions were diluted in a weighed 500 c.cm.
flask, provided with a stopcock and delivery tube, and were forced in or
out by purified air. All flasks and bottles used for making or keeping
solutions were steamed out for several days, after standing for some time
filled with a dilute alkali solution.
The water was made by redistilling ordinary distilled water, after add-
ing to it alkaline permanganate which had been previously boiled. It was
distilled from a steam-jacketed copper still, and condensed hot in a tin
condenser, a large part being allowed to pass away as steam. It was
collected only in two- or four-liter hard glass “Non-Sol” bottles furnished
by Whitall, Tatum & Co., and allowed to cool in these, as hot water dis-
solves ordinary glass appreciably. The first and last portions of the dis-
tillate were rejected. No water of specific conductance greater than
0.9 × 10−" at 18” was used in making up the solutions.
The salts used for determining the conductance-capacity were sodium,
and potassium chlorides and potassium nitrate. The sodium chloride was
made by precipitating Baker and Adamson “C. P.” salt twice with hydro-
chloric acid gas. The potassium chloride was made by precipitating the
“C. P.” salt furnished by Baker and Adamson with hydrochloric acid
gas, and crystallizing from hot water. The potassium nitrate was made by
twice recrystallizing “C. P.” salt from the same source. The salt gave
no test for sulphate or chloride.
In preparing the solutions, the sodium and potassium chlorides were
ignited in a platinum dish, the potassium nitrate dried at 130° to constant
weight; the proper quantity of salt was weighed out and dissolved in
a 2-liter flask, and the solution then diluted to the mark. The conductance
of a sample of the water used was tested at the same time. A fresh solu-
tion was made for every determination.
Ten liters of an approximately 0.1 normal solution of hydrochloric acid
were prepared from strong “chemically pure” acid, as a titration stand-
ard.* This was analyzed by precipitation with silver nitrate, and by
titration against a solution of sodium carbonate. prepared from pure
sodium bicarbonate, using methyl orange as indicator. The acidity deter-
mination was practically identical with the chlorine determination. The
value used was 90.46 milli-equivalents per kilogram of solution.f
*50 c.cm. of the strong acid were evaporated to dryness on a steam-bath; the resi-
due was organic, and amounted to only 0.01 per cent of the total hydrochloric acid.
30 c.cm., evaporated with barium chloride, gave no test for sulphate. The water
used in diluting it had at 18° a conductance less than 1.4 X 10-9.
#Derived from the following data:
Grams of solution. . . . . . . . . . . . . . . . . 93.84 104. 70 105.98 126. 59
Grams AgCl . . . . . . . . . . . . . . . . . . . . . . 1. 21.69 1.3579 1. 3748 1.6425
Milli-equivalents HCl per kilogram... 90.44 90.45 90. 47 90.49
Mean . . . . . . . 90.46. Average deviation = 0.02 per cent. By titration of Na2COs. .90.43.
Section 4.—Preparation of the Solutions. II
A barium hydroxide solution was prepared for the purpose of titrating
acetic acid solutions. This was found by titration against the standard
hydrochloric acid, using phenolphthalein and excluding carbon dioxide, to
have 80.73 milli-equivalents per kilogram of solution.*
The ammonia solutions were from two independent sources: first, a
special preparation of specific gravity 0.90, obtained from Baker and
Adamson, marked “free from amines, carbonate, and silicate”; second,
redistilled liquid ammonia. The solutions were made by filling a 6-liter
bottle with conductivity-water, displacing this completely with pure air,
then forcing in water of conductance less than 0.9 × 10−". When the
strong ammonia solution was used, it was introduced by means of a pipette,
under the surface of the water. When liquid ammonia was employed, it
was first drawn off into an iron cylinder and allowed to stand in contact
with metallic sodium for several weeks. From this cylinder it was dis-
tilled, passing through plugs of asbestos into a small glass bulb from
which the air had been previously evacuated; this bulb stood in a tube of
liquid ammonia, which was kept rapidly evaporating by a current of air
over the surface of the liquid. The ammonia within the bulb was thus
condensed until the proper quantity was obtained (about 15 c.cm.); the
air current was then stopped, the ammonia surrounding the bulb partly
removed, and the pure ammonia within was allowed to distill through a
plug of cotton directly into the water, through the exit tube of the bottle.
The last cubic centimeter was rejected. A procedure adopted later con-
sisted in distilling the ammonia from the iron cylinder into a flask contain-
ing solid ammonium nitrate, and kept in a freezing mixture. The nitrate
readily absorbs its own weight of ammonia, and the mixture has a rela-
tively low vapor pressure, so that the ammonia could be preserved in the
flask, which was closed by a glass stopcock, and could be redistilled there-
from at room temperature when needed.
The concentration was determined by titrating the standard hydro-
chloric acid with the ammonia, using as indicator at first phenacetolin,
and later Congo red, both of which gave a better end-point than methyl
orange. The solutions could not be kept long, as they began to increase
in conductance after about three weeks, probably because of action on
the glass, and they were not considered trustworthy after the conductance
had risen 0.2 per cent. The following list gives the date of making the
stock solutions, and the source from which the ammonia was obtained; the
number corresponds to that in table 6.
*Derived from the following data:
Grams HCl solution. . . . . . . . . . . . . . . . . . . . . . . . . 70.25 82.38 74.36
Grams Ba(QH)a solution . . . . . . . . . . . . . . . . . . . 78.76 92.39 83.36
Milli-equivalents per kilogram . . . . . . . . . . . . . . 80. 74 80. 76 80. 68
I2 The Hydrolysis of Ammonium Acetate, Etc.
(1) February 30, 1905. Same as stock solution No. 2 of Noyes and Kato (see
(2) A. y From Baker and Adamson's aqua ammonia used by Noyes and
(3) J º From a new supply of Baker and Adamson's aqua ammonia.
(4) June 10, and (5) June 16. From liquid ammonia.
(6) June 24. From same supply as No. 3.
(7) July 19, (8) October 16, and (9) November 2. From liquid ammonia.
(10) February 2, 1906, and (11) February 19. From liquid ammonia distilled
from ammonium nitrate.
(12) March 3. From a new supply of Baker and Adamson's aqua ammonia.
(13) May 22. From same supply as No. 11.
The acetic acid was made from a preparation of Kahlbaum, marked
“99 – 100 per cent.” This was twice fractionated by freezing, and once
distilled, the yield being 200 grams out of 625. The distillate was received
in three fractions. Solutions Nos. 1 and 2 (July 14, 1905) were made from
the second and third fractions respectively. No. 3 (July 18) was from the
same acid as No. 2, redistilled once. Nos. 4 (October 9, 1905) and 5
(May 6, 1906) were from the same acid as No. 1, redistilled twice. No.
6 (May 12, 1906) was made from a new supply of the Kahlbaum acid,
redistilled three times, the portion used distilling at 117.7° to 118.0°. The
concentration was determined by titrating the standard barium hydroxide
with the acid, using phenolphthalein as indicator and excluding carbon
dioxide.
The ammonium acetate solutions were made by mixing weighed quan-
tities of the ammonium hydroxide and acetic acid solutions in such propor-
tion as to form a neutral solution. Large enough quantities were taken
to make the error of weighing negligible. Solution No. 1 was made from
ammonia No. 7 and acid No. 3; No. 2, from ammonia No. 8 and acid No. 4.
The same solutions were used in adding an excess of acid or base as were
used in making the neutral salt solution, except in the experiments fol-
lowing Expt. No. 2.18; in these, acid solutions Nos. 5 and 6, and ammonia
solution No. 13 were used.
The ammonium chloride was made by first subliming Baker and Adam-
son “C. P.” salt, “free from traces of hydrocarbons,” then recrystallizing
this salt three times. Part of the salt was dissolved in water of specific
conductance 0.8 × 10−", and the concentration of this solution (No. 1)
found by precipitation with silver nitrate to be 100.8 milli-equivalents per
kilogram.* For comparison, solution No. 2 was made by mixing the
proper quantities of standard hydrochloric acid and ammonia No. 9.
The sodium acetate was made by recrystallizing J. T. Baker’s “C. P.”
analyzed preparation, the analysis being given as “no iron or other metals,
*Derived from the following data:
Grams of solution. . . . . . . . . . . . . . 109. 29 113. 07 121.24
Grams AgCl . . . . . . . . . . . . . . . . . . . 1. 5800 1.6337 1.7518
Milli-equivalents per kilogram. . . . 100.83 100. 77 100. 77
Section 5.-Errors in the Solutions and their Correction. I3
no sulphates, 0.0006 per cent C1.” The recrystallized salt was dissolved
in water of specific conductance 1.1 × 10−", and the concentration of the
solution was found, by evaporation with pure hydrochloric acid and gentle
ignition to constant weight, to be 112.2 milli-equivalents per kilogram.*
5. ERRORS AFFECTING THE SOLUTIONS AND THEIR CORRECTION.
The effect of carbon dioxide on the conductivity of ammonium hydrox-
ide solutions can be shown to be very large. Thus, the ammonium carbo-
nate formed by the addition of 0.01 per cent (in mols) of carbon dioxide
to a 0.1 molal ammonium hydroxide solution is not appreciably hydrolized,
on account of the large excess of ammonia present; considering it there-
fore as being completely ionized, and taking the equivalent conductances
of NH, and CO, as 64 and 70 respectively, the increase in the specific
conductance of the 0.1 molal ammonia solution, caused by the addition
of the carbon dioxide, is found to be 2.7 × 10−", or 0.9 per cent of that of
the ammonium hydroxide. That even such a small amount, which would
of course vary considerably, was not absorbed during the filling of the
bomb, is shown by the fact that successive determinations of the resistance
of the same solution agree at 18° within 0.1 per cent.
The error due to carbon dioxide in the water used for making the solu-
tion or in the strong ammonia solution itself, is almost impossible
to determine. Water at 17° absorbs its own volume of carbon dioxide
at atmospheric pressure; ordinary air contains about 0.04 per cent CO2
by volume, hence water in equilibrium with ordinary air will contain
17 × 10−" mols of un-ionized H,CO, per liter. Using Walker'sf value
of 3040 × 10−4° for the ionization-constant of H2COs into H+ and
HCOs", and taking for the equivalent conductances of these ions 320
and 50, respectively, the specific conductance of this water should be
0.8 × 10−". The specific conductance of the water actually used was
always less than 1.0 × 10−", usually less than 0.8 × 10−"; but it is very
unlikely that this water was saturated, since it was condensed hot, and
afterward kept protected from the air. Hence the larger part of the
conductance found was probably due to organic bases which distil over
with the water, or to salts carried over mechanically by the current of
steam. The view that it is not due to carbonic acid is supported by the
fact that ammonium hydroxide solutions made from water varying in con-
ductance from 0.5 × 10−" to 0.8 × 10−" show, after subtracting the con-
ductance of the water, values for the equivalent conductance constant
*Derived from the following data:
Grams of solution. . . . . . . . . . . . . 114. 97 118.84 120. 42
Grams NaCl . . . . . . . . . . . . . . . . . . 0.7540 0.7799 0.7916
Milli-equivalents per kilogram . . 112.10 112.18 112.37
f2. phys. Chem., 32, 137 (1900).
I4 The Hydrolysis of Ammonium Acetate, Etc.
within 0.1 per cent. Samples of the water, after being heated to 218° or
306°, showed an increased conductance at 18°, and were not changed by
further heating, indicating the presence of a small amount of some organic
substance, which was decomposed or oxidized at the high temperatures.
If originally present in the strong ammonium hydroxide solution from
which the diluter solution was made, carbon dioxide of course would have
the same effect as if present in the water, in giving too high a value. In
fact, practically any imaginable impurity in the strong solution would have
the effect of increasing the conductance, so that the lowest value obtained
should be considered the most accurate one.
In the first experiments made with ammonium hydroxide, as will be
shown later in the data, the specific conductance had always decreased
about 1.9 per cent at 18°, after the heating to 218°. The first three experi-
ments were made without exhausting the air from the bomb; in the third,
the bomb was twice reheated, causing further diminutions of 0.6 per cent
and 0.25 per cent. In the fourth experiment the air was exhausted down
to 4 cm. pressure, which reduced the decrease after the heating to 1.3 per
cent. In all cases there was a slight suction when the bomb was opened.
These facts show that some change occurred at the higher temperature
which caused a permanent decrease in the conductance. Any contamina-
tion would be almost certain to increase it. There was no leak, for the
conductance at the upper electrode remained perfectly constant. There was
no escape of ammonia through the platinum, for the effect did not con-
tinue to an appreciable extent after the second heating. Adsorption by
the platinum is not likely, for the effect was almost exactly the same in
each run. The most probable explanation is that the oxygen left in the
vapor space, in solution, and on the platinum surface, oxidized part of the
ammonia to nitrogen and water; this would account also for the decrease
of pressure within the bomb, as is evident from the following equation:
4NH4OH + 3 O2 = 2N2 + 10 H2O, which shows a decrease of one mol
of gaseous substances.
The oxidation of ammonia in the presence of platinum black seems to be
a well established phenomenon. Henry” observed that platinum sponge
caused slow oxidation in a mixture of ammonia and oxygen at 193”.
Mond, Ramsey, and Shields; removed oxygen from spongy platinum by
this reaction. Vondráceki: found that an 0.087 normal solution is oxidized
by platinum sponge at ordinary temperatures; boiling solutions of ammo-
nium salts are also oxidized by it. Platinum containing no oxygen had a
slight reducing action.
*Ann. Philos., 25, 424 (1825).
†Z. phys. Chem., 25, 657 (1897).
£Z. anorg. Chem., 39, 24 (1904).
Section 5.-Errors in the Solutions and their Correction. I5
This difficulty can be partly removed, of course, by pumping the air
out as completely as possible. This causes no appreciable loss of ammo-
nia, since its partial pressure above a 0.1, normal solution at 18" is only
1.34 mm;” hence the ammonia present in 20 c.cm. of the vapor above the
solution is only 0.01 per cent of that in the solution. But some oxygen
still remains dissolved in the solution and in the platinum, and causes
oxidation of the ammonia. Hence the most feasible plan was to pump out
the air before the heating till the pressure became 2 or 3 cm., and to
determine after the heating the strength of the solution, by titrating the
solution left in the bomb.
There is some error in the titration of an ammonia solution so dilute as
0.01 normal, as the end point is not sufficiently sharp. The method used
was to adopt a standard color, add an excess of acid to a portion of the
solution, and titrate to the standard color with the residue of the solution.
The percentage error of the titration was at the same time determined by
titrating similarly a portion of the unheated solution, whose concentra-
tion was known. Solutions 6.1 and 6.2 were titrated with phenacetolin,
the correction for the titration-error being + 1.0 per cent; the other dilute
solutions were titrated with Congo red, for which correction was — 0.3
per cent.
In the first experiments with ammonium acetate, the conductance at
18° was also found to have decreased from one to two per cent as a result
of the heating at 218°. Experiments with acetic acid showed that this was
not alone due to the oxidation of ammonia, but that the acetic acid itself
had decreased both in conductance and ‘concentration after being heated
to 218°. This effect was not sufficiently marked to be taken account of in
the work of Noyes and Cooper, probably because in their small tempera-
ture-bath the solution could be heated to constant temperature much more
quickly, and also because they used unplatinized electrodes, platinum black
being a catalyzer of the decomposition, according to the work of Sabatier
and Senderens.f. In the heatings to 306° this effect was found to become
greater with increased concentration of the ammonium acetate solution.
It seemed possible that it might be due to the formation of acetamide at
the high temperature and the continued existence of this in the solution
at 18° owing to the rapid cooling. If this were the case, it should be pos-
sible to reconvert it to ammonium acetate by prolonged heating at about
100°. Two hours heating of one of the solutions at 110°–120°, however,
produced only a slight decrease, instead of an increase, in the conductance
at 18°. The existence of acetamide in the solutions at the high tempera-
tures would give rise to an error in the calculated hydrolysis. That it does
*Locke and Forsell, Am. Chem. J., 31, 268 (1904).
fAnn. chim. phys. (8), 4, 319, 433.
16 The Hydrolysis of Ammonium Acetate, Etc.
not exist in significant quantity even at 306° is shown, however, by the
agreement of the ionization-constants for water derived from the experi-
ments with salt solutions of very different concentrations, since in these
the percentage of acetamide should vary greatly, owing to its being pro-
portional to the product of the ammonium and acetate ion concentrations.
It was found very difficult to analyze accurately the ammonium acetate
solutions left in the bomb. The ammonium content could be determined
within 0.2 per cent by making the solution alkaline with sodium hydroxide
and distilling off the ammonia into standard sulphuric acid; but even this
accuracy could not be obtained in determining the acetic acid. The proced-
ure was therefore changed so as to make the oxidation as small as possible.
After the initial 18° measurement, the bomb was set in water at 60°, and
was kept evacuated for two or three minutes down to a pressure of a few
centimeters; this caused the solution to boil vigorously, so that nearly all
the air was carried out of the bomb. Several determinations of the con-
ductance at 18° after this treatment, showed an increase of only 0.2 to 0.3
per cent caused by evaporation of water. It is probably safe to assume
that in the pure ammonium acetate solutions there was no appreciable loss
of ammonia from the salt, because the hydrolysis is less than 3 per cent
and the vapor pressure of ammonia therefore practically inappreciable,
and also because the observed change in conductivity was so small. In
the solutions containing an excess of ammonium hydroxide or acetic acid
the loss of these substances that probably occurred by vaporization is not
important, since the concentration of the excess of acid or base needs to
be known only approximately. The oxidation at 218° was thus reduced
to 0.5 per cent or less. This change in concentration can be corrected for
accurately enough by assuming that the change of concentration of ammo-
nium acetate is proportional to the change of specific conductance at 18°.
In all the experiments at 306° the same procedure was followed, but the
loss by oxidation of the salt could not be kept so low. It was necessary,
also, to determine the excess of ammonium hydroxide or acetic acid after
each experiment, since the addition of one equivalent of base or acid at
306° produces a much greater change in the hydrolysis and conductance
than at 218°. The only practicable method found was to empty and dry
the bomb, replace in it a weighed quantity of the solution, weigh in enough
acetic acid (or ammonium hydroxide) solution to slightly exceed the free
ammonium hydroxide (or acid) present, and determine the conductance
of this mixture. Since a small excess of acid or base has no appreciable
conductance, the total concentration of the ammonium acetate could be
calculated from this conductance; and by subtracting from this the con-
centration of salt at the end of the experiment, as given by the final
conductance at 18°, there was obtained the concentration of free ammo-
Section 5.-Errors in the Solutions and their Correction. 17
nium hydroxide (or free acetic acid) in the solution investigated. It was,
however, found that, with solutions containing an excess of acid, this
excess underwent no considerable change during the heating. That the
method is accurate within 0.1 per cent was shown by an analysis of a
known ammonium acetate solution containing a known excess of ammo-
nium hydroxide.
This procedure of boiling the solution to remove all air was not used
with pure ammonium hydroxide, acetic acid or sodium acetate, because
there was no especial advantage in it, since it was in any case necessary to
titrate the solution after the heating. The procedure was used, however,
in the experiments with ammonium chloride; the correction on the concen-
tration for the vaporization of water was found to be the same as in the
ammonium acetate solutions, viz., about 0.3 per cent. In the experiments
with ammonium chloride at 306° the concentration of the excess of ammo-
nium hydroxide after the experiment was determined by titration against
hydrochloric acid. &
The measured conductance of the solution includes that of the water
and of the small amount of impurities left in the water. The initial 18°
values were corrected by subtracting the conductance, measured in a small
Arrhenius cell, of the particular sample of water used in making the solu-
tion; for the most probable effect of the impurities is to increase rather
than to decrease the conductance of weak acids and bases. As a basis for
the correction at the higher temperatures the specific conductance of the
water and its impurities was determined by making several heatings with
pure water, following exactly the same procedure as in the regular experi-
ments. Both my results (reported in this section) and those obtained
in the other investigations of this series show that the conductance at the
higher temperatures does not vary much in successive runs, and that it
is not proportional to the conductance at 18°.
At 18° the measured conductance of the water is due almost entirely to
the impurities, that due to the hydrogen and hydroxide ions being inap-
preciable; but at 218° and 306° the latter forms a considerable part of the
whole. Its amount was determined from a preliminary value of the ioni-
zation-constant (Kw) of water, by the formula L = 10−"CH (AH + AoE)
where C# (equal to VKw) is the concentration, in equivalents per liter,
of the hydrogen (or hydroxide) ions in pure water, and (AH + AoE) is
the sum of the equivalent conductances of hydrogen and hydroxide ions,
calculated by adding the Ao value for sodium hydroxide to the difference
between the Ao values for hydrochloric acid and sodium chloride,
18 The Hydrolysis of Ammonium Acetate, Etc.
Table 1 gives the conductance of the water as actually measured in the
bomb and its specific conductance at the temperatures 18°, 218°, and 306°.
TABLE 1.—Conductance of water.

Conductance X 106. Specific conductance X 106.
O O
Date. 18 218° 18 218.9
Initial. Final. Initial. Final
1905
NOVA 13. . . 5.5 7.1 43.8 0.85 1.05 6. 55
NOV. 14. . . 4.4 7.1 35.4 0.65 1.05 5.3
NOVA 14. . . 3.2 9.4 36.2 0.45 1.4 5.4
NOW. 15. . . 5.3 9.8 4.1.1 0.8 1. 5 6.15
Mean . . . . . . . . . . . . . . . . . . . . . . . . 0.7 1.25 5.85
1906 306°. 306°.
June 4 ... 6.7 26.9 46.1 1.0 3.9 6, 8
June 5 ... 6.2 7.6 85.7 0.9 1.1 5.2
June 19 . . . 7. 9 17.5 70,0 1.2 2.7 10.7
June 20 . . . 6.3 61.5 78.7 0.9 9.4 *12.0
June 28 . . . 8.0 25, 5 68.3 1.0 3.9 10.4
Mean . . . . . . . . . . . . . . . . . . . . . . . . 1.0 3.6 8.7
.*This experiment was given a weight of one-half, because of the abnormally
high final conductance at ©
The data and results of the calculation of the conductance due to hydro-
gen-ion and hydroxide-ion are as follows:
Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218° 306°
AH + AOH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1565 1654
Specific conductance X 10° of conductivity water...... 5.85 8.7
6& & 6 X 100 of H and OH ions. . . . . . . . . 3.35 2.1
© {& X 10° of impurities . . . . . . . . . . . . . . 2.5 6.6
The observed conductance of the solutions was in every case corrected
by subtracting the conductance of the impurities. The fraction which this
conductance forms of the conductance of the 10 milli-normal ammonium
chloride or sodium acetate solutions is about 0.1 per cent at 18°, 0.03
per cent at 218°, and 0.05 per cent at 306°; and of that of the 100 milli-
normal ammonium hydroxide or acetic acid is about 0.2 per cent at 18°,
0.6 per cent at 218", and 4.0 per cent at 306°.
The correction for the conductance of ionized water at 218° and 306°
still remains to be considered. In the solution of pure ammonium hydrox-
ide and acetic acid this correction is negligible, even in the most dilute solu-
tions, since the ionization of the base or acid is still sufficient to drive that
of the water back to an inappreciable quantity. In the solutions of pure
ammonium acetate, where very nearly equal quantities of acid and base
are produced by the hydrolysis, the conductance of the hydrogen and
hydroxide ions as given in the preceding table was directly subtracted. In
Section 5.—Errors in the Solutions and their Correction. I9
the case of the ammonium chloride and the sodium acetate solutions at
218° or 306° this correction is conveniently calculated in combination with
the correction for the hydrolysis of the salt, which is not entirely negligible
even in the presence of the excess of ammonium hydroxide or acetic acid
added. And in the case of the ammonium acetate solutions containing an
excess of ammonium hydroxide or acetic acid at 218° and 306°, the water
correction is best combined with that for the conductance of the excess
of base or acid present. Thus in the solutions of ammonium chloride or
acetate containing an excess of the hydroxide, the concentration of un-
ionized ammonium hydroxide is approximately equal to the concentration
of the ammonium hydroxide added (CB) plus that (Ch) arising from the
hydrolysis of the salt (the latter term Ch being negligible in the case of
the chloride); and that of the ammonium-ion is given approximately by
the ratio (multiplied by 10°) of the specific conductance of the solution
(L), to the equivalent conductance Ao of the completely ionized salt. The
combination of the expressions of these two facts with the mass-action
equations for ammonium hydroxide and water gives the formulas:
KBAo(CB -- Ch) and CH = Kw
L CoH
where the concentrations (both those given directly and those involved in
KB and Kw) are expressed in equivalents per liter. In the ammonium
chloride solutions part of the hydrogen corresponds to the excess of
chloride-ion over ammonium-ion, the remainder to the hydroxide-ion in the
solution; hence the correction to be subtracted from the specific con-
ductance is:
10 *[CoH (AH + AoE) + (CH – CoH) (AH + Aci)]
In the ammonium acetate solutions, on the other hand, part of the
hydroxide-ion corresponds to the excess of ammonium-ion over acetate-
ion, and the remainder to the hydrogen-ion in the solution; hence the cor-
rection to be subtracted is:
10 * [CH (AH + AoE) + (CoH – CH) (ANR, + AoE)]
The calculations are in every way similar for sodium acetate and for
ammonium acetate with excess of acetic acid, KA and CA being sub-
stituted for Ke and CE, and CH for CoH ; the correction to the specific
conductance then becoming º
107* [CH(AH + AoH) + (CoH — CH) (ANA + AoH)]
for sodium acetate, and
10 * [CoH (AH + AoH) + (CH – CoH) (AH + AAe) ||
for ammonium acetate,
CoH – 10-8
2O The Hydrolysis of Ammonium Acetate, Etc.
At 18", in the solutions of ammonium chloride and sodium acetate,
the ionization of water is so small that the above mentioned hydrolysis
correction entirely disappears; on the contrary, the conductance of the
added base or acid itself must be subtracted. This correction is cal-
culated by the mass-action law to be
10-ºk BCB (ANH, # Aci) (ANH, -H AoH)
for the ammonium hydroxide in the ammonium chloride solution, and
10-K,c, *, +**# AAc
solution; where KB (or KA) is the ionization constant of the base (or
acid), CE (or CA) is the concentration of the added base (or acid) in
equivalents per liter, ANH, Aci and AoE (or ANA, AA, and AH) are the
equivalent conductances of the respective ions, and L is the specific con-
ductance of the salt in the mixture.
The effect of the excess of acid or base upon the ionization of the salt
remains to be considered. In almost all cases this is negligible, as is
apparent from the smallness of the correction for its conductance; but
in the dilute solutions of ammonium chloride and sodium acetate at 18°,
the concentration of the common ion from the added base or acid is
sufficient to diminish appreciably the ionization of the salt itself, so that
the conductance obtained by subtracting that of the base or acid is not
the true conductance of the salt at the concentration in question. How-
ever, no correction was applied for this, since these 18° measurements
were made only to show whether any contamination or change had taken
place in the solution during the heating.
The concentration is diminished in the case of the more volatile solutes
by the volatilization of a small amount of the solute. In the case of
acetic acid at 218°, Noyes and Cooper (section 49, Part V) have already
shown that the concentration is not appreciably affected by vaporization
into the small vapor-space of 2 or 3 c.cm. usually present. The total cor-
rection to be applied to the concentration for the vaporization of both
water and solute was directly determined for ammonia at 218° and 302°
and for acetic acid at 306” by measuring the difference in conductance
produced by increasing the vapor-space from 2 c.cm. to 30 or 50 c.cm.
Without describing the details of the experiments or of the calculation,
the results may be stated. It was found that the correction to be made
on the concentration per cubic centimeter of vapor-space in the case of
ammonium hydroxide solutions is — 0.025 per cent at 218° and — 0.12
per cent at 302° or 306°, and in the case of the acetic acid solutions is
— 0.05 per cent at 306°. Thus the correction is negligible at 218° for the
ammonium hydroxide just as for acetic acid, and is small for both sub-
stances even at 306°.
(AH + AAC) for the acetic acid in the sodium acetate
|
Section 6–Specific-Volume Data. 2I
6. THE SPECIFIC VOLUME, DATA.
To change the concentration by weight to concentration by volume
at the temperature (t) of the measurement, the number of milli-equiva-
lents per kilogram of solution was multiplied by the density of the solu-
tion at 4° and by the ratio of the specific volume at 4° to that at t”. The
density was taken as unity in most cases, but special values were used
in the case of solutions stronger than 0.04 normal.”
Noyes and Coolidgef have found that sodium and potassium chlo-
rides in 0.1 normal solution have substantially the same specific-volume
ratio at 306°, and that this specific-volume ratio differs from that of
water by only 1.0 per cent. Since the solutions of ammonium chloride,
sodium acetate, and ammonium acetate used in the present work were
all less than 0.03 normal at 306", it was considered unnecessary to deter-
mine the specific-volume ratios for them; but these were assumed to be the
same as for sodium and potassium chlorides, and the deviation from the
ratio for pure water was assumed proportional to the concentration. At
18°, in all cases, the specific-volume ratio for pure water, 1.0013, was used.
For ammonium hydroxide and acetic acid, determinations of the
specific-volume ratio were made at the highest temperature on solutions
sufficiently strong to show the deviation from pure water. For correc-
tions at smaller concentrations, and at 218°, the deviation from the ratio
for pure water was assumed proportional to the concentration and to the
temperature difference. The error introduced by this assumption can not
be greater than 0.1 per cent.
The procedure for determining specific volume was the same as that
employed by Noyes and Coolidge. In table 2 the first column gives
the date; the second, the concentration in milli-equivalents per kilogram
of solution; the third, the weight (in vacuo) of the solution in grams;
the fourth, the temperature of measurement (t”); the fifth, the volume
of the solution at this temperature; the sixth, the weight of solution cor-
rected for vaporization into the vapor-space; the seventh, the specific
volume of the solution at t”; the eighth, the specific volume corrected to
302° (or 306°) by adding 0.0043 per degree; and the ninth, the ratio of
the specific volume at t” to that at 4°.
*The values of the density employed are as follows:
Ammonia . . . . . . . . . . . . 0.1 normal 0.9992 Determined by pycnometer.
Ammonia . . . . . . . . . . . . . 0.5 normal 0.9961 Lunge et al., Landolt-Börnstein-Meyerhoffer”
Tabellen, 329 (1905). y S
Acetic acid . . . . . . . . . . . . 0.1 normal 1.0011
Acetic acid . . . . . . . . . . . . 0.5, normal 1.0042 Reyher, ibid., p. 344.
Ammonium chloride . . . . 0.04 normal 1.0007 Dijken, ibid., p. 336.
Sodium acetate . . . . . . . . 0.04 normal 1.0020 Franz, ibid., p. 335.
Ammonium acetate . . . . . 0.04 normal 1.0008 Hager, ibid., p. 320.
#Section 12, Part II.
22 The Hydrolysis of Ammonium Acetate, Etc.
The specific-volume ratio for water at 302° is 1.417; at 306° 1.4365.
The values for the ammonium hydroxide and acetic acid solutions there-
fore differ from that for water by 1.5 per cent and by 0.6 per cent
respectively.
The two determinations of the volume of the bomb, made for the
above measurements, gave 127.9 c.cm. and 128.0 c.cm. respectively for
the volume at zero, which corresponds to 129.5 c.cm. at 306°. The values
of the thermal expansion-coefficient of the bomb, by means of which the
latter value was calculated, are reported in section 21, Part III.
TABLE 2.-The specific-volume data.

AMMONIUM HYDROXIDE.
Milli-equiv-| Weight Tempera- || Volume at | Weight Specific volume
Date. alents per of ture (19) go at tº O O Ratio
kilogram. solution. & ſº g At tº. At 302°. 36.3.3.
1906
Feb. 27 . . 523 88.69 || 300.8 || 127.48 88.61 | 1.4387 | 1.444 1.438
Mar. 3 . . 513 88. 56 301.5 127.61 88.49 | 1.4421 | 1.4445 | 1.4385
Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4385
ACETIC ACID.
Specific volume
Dat º: wº Tempera- Volume at Weight
C. alents per O ture (tº). zo, at tº.
kilogram. solution. At t°, At 306°, 306°|4°
1906
May 13 . . 431 88.13 305.1 | 126. 54 88.02 | 1.4376 | 1.4415 | 1.447
May 15 . . 431 88.60 306.0 | 127.36 88.53 | 1.4386 | 1.4385 | 1.444
Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4455
7. CONDUCTANCE-CAPACITY OF THE APPARATUS.
The conductance-capacity was determined by measuring the conduct-
ance in the bomb of solutions of known strength, and dividing these
values into the known specific conductance of the solutions as deter-
mined by Kohlrausch.* These solutions were made to contain at 18"
an exact number of equivalents in one liter. In table 3, the fifth
column gives the measured conductance of the solution; all the measure-
ments in 1905 having been made at 17.95°, those in 1906, at 18.00°.
The sixth column gives the conductance reduced to 18.00° and corrected
for the conductance of the water. The seventh and eighth give the
conductance-capacities at 18°, and at 218° or 306° respectively.
*Sitzungsber. königl. preuss. Akad., 1900, 1002. The values used were:
Potassium chloride, § :#s normal, # .43
41
Potassium nitrate, 0.01 118.19
0.005 120. 47
Sodium chloride, ; 01 101.95
Section 7.—Conductance-Capacity of the Apparatus.
TABLE 3.-Values of the conductance-capacity.
23

Conductancel Date Salt. Milli-equivalents Conductance X 100. Conductance-capacity.
vessel. g per liter. Observed. | Corrected. 189 218°
1905 *
Bomb 4 |Apr. 6 ...|KCl.... 10.00 8,171 8,172 0.14983 e e º O C.
KCl... . 10.00 8,175 8,176 0.14974 © C C º
FCCl.... 10.00 8,173 8,174 0.14977 g º e º 'º e
Apr. 7 . . KCl... . 10.00 8,171 8,172 0.14983 | . . . . . .
Apr. 8 ...|KNOa. 10.00 7,888 7,889 0.14982 . . . . . . .
Mean ..] . . . . . . . . . . to gº º ºs º 'º e º gº tº º º 0.14980 || 0.14941
Bomb 4 |July 22 ... KCl.... 10.00 8,154 8,157 0.15010 tº e Q & G G
July 23 ... [KCl.... 5.00 4,147.5 4,146.5 0.15002 | . . . . . .
July 24 ...|KNOa.. 5.00 4,023.5 4,019.5 0.14985 . . . . . . .
NaCl... 10.00 6,802 6,801.5 0.14989 . . . . . .
Mean . . . . . . . . tº e g tº e I e g º a G is o e º O G. G. 0.14997 || 0.14958
1906 — 306
Bomb 4 Feb. 12 ... KCl.... 10.00 8,228 8,220 0.14894 | . . . . . .
NaCl... 10.00 6,855 6,847 0.14890 g º Q & © G
Mean . . . . . . . . . . . . . . . . . . . . . . . . . . 0.14892 || 0.14828
Bomb 4 |*Feb. 12 . |FCCl.... 10.00 8,191 8,183 0.14962 tº ſº º ſº G &
NaCl... 10.00 6,824.5 6,816.5 0.14956 . . . . . .
Mean . . . . . . . . . . . . . . . . . . . . . . . . . . *0.14959 | . . . . . .
Bomb. 4 Mar. 2 ... [NaCl... . 10.00 6,950 6,942 0.14686 C & © tº º
Mar. 11 ... KCl.... 10.00 8,351 8,344 0, 14673 tº tº º ſº ºn tº
Mean ..] . . . . . . e g º ºs º g º ºs e > || > º e º O ſº 0.14680 0.14617
Bomb 4 Apr. 23 ...|KCl.... 10.00 8,342 8,334 0.14691 . . . . . .
May 16 . . KCl.... 10.00 8,342 8,334 0.14691 | . . . . . .
June 6 . . KCl.... 10.00 8,355 8,346 0.14669 | . . . . . .
Mean . . . . . . . . . . . . . . . . . . . . . . . . . . 0.14687 || 0.14624
Bomb 3 June 22 ... KCl... . 10.00 7,990 7,981 0.15340 | . . . . . . .
KCl.... 10.00 7,987 7,980 0.15343 | . . . . . .
|Mean ..] .... . . . . . . . . . . . . . tº tº ºn tº e º º 0.15341 || 0.15275
Bomb 3 June 25 . . |FCC1... . 10.00 8,010 8,002 0.15300 0.15234
Bomb 3 June 29 . . KCl.... 10.00 8,021 8,013 0.15280 | . . . . . .
July 2 ...|KCl.... 10.00 8,015 8,008 0.15280 . . . . . . .
Mean . . . . . . . . . tº º ºs ſº tº e º dº º e º ſº gº tº G 0.15284 0.15218
Bomb 3 July 3 ...|KCl.... 10.00 912. 5 911.6 1.3431 1.3346
1905
Pipette- July 12 ...|RCl.... 10.01 2,619.5 2,620.4 0.4679 © tº ſº º te tº
Cell RCl.... 10.01 2,621.5 2,622.4 0.4674 tº C tº gº tº Q
NaCl... 9.99 2,176.8 |2,177.1 0.4678 e g º O ſº gº
July 13 . . NaCl... 20.00 4,258.3 4,259.9 0.4677 tº G & ©
RNO,.. 10.00 2,527.0 | 2,527.6 0.4676 | . . . . . .
Mean ..] . . . . . . . . . . . . . . . . & 1 C C º - G - 0.4677 o º ſº G. G.
*In this case the bomb contained only 60 c.c.m. of solution.
The comparison of the first two mean values in table 3 shows an
increase in the conductance-capacity of only 0.1 per cent in four months;
and the close agreement in the specific conductance of the same ammo-
nium chloride solution, measured in the bomb and in the pipette cell
at the close of the measurements at 218° (see table 4, experiments
1.5 a and 1.5 b) shows that the conductance-capacity had remained prac-
tically constant up to that time. But when redetermined after the first
24 The Hydrolysis of Ammonium Acetate, Etc.
five experiments at 302° (see table 6, experiments 10 a - 10 e) the con-
ductance-capacity had decreased by 0.65 per cent. A comparisof, of the
initial data at 18° of these five experiments showed that three-fourths of
this change took place at the first heating to 302°, which was made for
the purpose of steaming out the bomb. The remaining 0.2 per cent
change was therefore distributed equally over the five experiments.
Just before March 2, 1906, the lower electrode was removed, replaced,
and replatinized, the conductance-capacity being thereby changed. The
succeeding determinations show that it remained constant at the new
value. The last two determinations of February 12, 1906, in table 3,
were made with only 60 c.cm. of solution in the bomb. The conductance-
capacity was increased 0.45 per cent by this change in the depth of the
solution; it was found independent of the depth when the volume of the
solution exceeded 85 c.cm. (See page 9). g
The electrode of bomb No. 3 was replatinized after the experiment
of June 20, 1906, and was removed, replaced, and replatinized before the
experiment of June 28, the conductance-capacity being changed slightly
each time. On July 3, the cylindrical electrode was removed, and a
quartz cup put in, for work with the stronger ammonium chloride and
sodium acetate solutions.
8. THE CONDUCTIVITY DATA.
In the following tables are recorded the data actually observed,” which
form the basis of subsequent theoretical calculations. For convenience
there are also included in these tables the corrections for impurities in the
water, and for the residual hydrolysis or for the added base or acid in
the case of ammonium chloride and sodium acetate, which corrections
were discussed in section 5.
The first column gives the date of the experiment. The second gives
the number of the experiment; the figure before the decimal point is the
number of the stock solution, that after the decimal point the number
of the dilute solution prepared from the stronger one; successive runs
with the same solution are designated by appending the letters a, b, etc.
In the next column or columns is given the concentration of the solute
or solutes in milli-equivalents (referred to the oxygen-equivalent as
8.000) per kilogram of solution. The column headed temperature (t)
*Ten experiments at 218°, and fifteen at 306°, were rejected on account of leakage
of solution out of the bomb. The initial 18° measurements on these solutions were
usually not affected, and have therefore been included among the data. Three other
experiments at 218°, and one other at 306°, were not used in deriving final values
on account of an abormal difference between the initial and final conductances at
18°; but the data of these experiments are given for the sake of completeness. In
addition, several measurements with ammonium acetate at 218° have been omitted,
because a more complete and accurate series was made later.
Section 8.-The Conductivity Data. 25
{ º
.*
gives the temperature of the measurement in degrees centigrade on
the hydrogen scale. The next column gives the measured conductance
in reciprocal ohms, multiplied by 10° and corrected for calibration and
lead resistance. (The letter G shows that the data were obtained in the
glass cell of pipette form.)
In tables 4 and 5, the next four columns give the values of the
specific conductance multiplied by 10°. The first of the four gives the
uncorrected value, obtained by multiplying the measured conductance by
10° and by the conductance-capacity given in table 73 for the date next
preceding that of the experiment; the second gives the values obtained
from these by subtracting the conductance of the impurities of the water
given on page 18; and the third and fourth give the same values fur-
ther corrected as described in section 5 for the conductance of the
added base (or acid) at 18° and for the ionized water and residual hydrol-
ysis at the higher temperatures. The last column gives the equivalent
conductance, calculated by dividing the corrected specific conductance
by the number of equivalents per liter at t”. These last were derived
from the milli-equivalents per kilogram as described in section 6, and are
given in tables 10 and 11. p
In tables 6 and 7 the sixth and seventh columns contain the specific
conductances, uncorrected, and corrected for the conductance of the
impurities in the water. The last two columns contain the correspond-
ing equivalent conductances. Both are given since there may be some
question in these cases as to the way in which the water correction should
be applied.
In table 8, which contains the results with ammonium acetate, the
equivalent conductances are not given, since the subsequent calculations
are based on the specific conductances. The last column of the table
gives the percentage change of the specific conductance at 18", due to
Oxidation or decomposition. The values of milli-equivalents of salt per
kilogram corresponding to the conductance at the higher temperature and
to the final conductance at 18° were obtained from the initial content by
changing it by a percentage amount equal to the above mentioned
percentage change in conductance. No similar correction was applied
to the acid or base content, except in the case of the experiments carried
to 306” with solutions containing an excess of base, in which case the
change in content was directly determined, as described in section 5,
to be that given in the table.
26 The Hydrolysis of Ammonium Acetate, Etc.
TABLE 4.—Conductivity data on ammonium chloride.
Ex- Milli-equivalents Tem- Specific conductance X 106. Equiv-
Date. ... ** | *... ..., unsel. Cºrrected to j
* | NH4c1. NH4OH. | *. *** | *|Nhloh...º. º
1905
NOV. 17|1.1 10.90 | . . . . . . 17.98| 2,845 G| 1,330.5| 1,329.5|. . . . . . . . . . . . 122.15
10.90 | . . . . . . 25.00 3,288 G| 1,538 | 1,537 . . . . . . . . . . . . . 141.35
Nov. 19:1.2a || 2.359 1.21 || 17.98 2,009 301.4 300.8. 298.6] . . . . . . 126.8
Nov. 2011.2b | 2.359 1.21 17.98 2,010 301.5 300.9| 298.7] . . . . . . 126.85
2.366 1.21 218.1 |10,760 1,610 | 1,607.5 . . . . . . 1,601 802.6
2.366 1.21 17.98| 2,041 306.1} 304.8; 302.6] . . . . . . . 128.1
NOW. 21|1.3a. 2.241 1.21 17.98. 1,911 286.6] 285.9| 283.7| . . . . . . 126.75
2,248 1.21 (218.6 10,240 1,531.5' 1,529 |. . . . . . 1,522.5| 804.0
2,248 1.21 17.98. 1,922 288.2| 286.9| 284.7 . . . . . . 126.85
NOW. 22|1.3b ; 2.241 1.21 || 17.98. 1,917 287.5| 286.8; 284.6] . . . . . . 127.2
2.248 1.21 (218.3 |10,255 1,534 || 1,531.5|. . . . . . 1,525 805.0
2,248 1.21 || 17.98| 1,929 289.2| 287.9| 285.7] . . . . . . 127.3
NOW. 22.1.4 || 10.03 5.95 17.98| 8,224 1,233.5| 1,232.5|1,230 | . . . . . . 122.8
10.06 5.95 |218.2 43,470 6,503 6,500 |. . . . . . 6,494 765.9
10.06 5.95 || 17.98; 8,263 1,239 || 1,238 1,235.5 . . . . . . . 123.0
NOW. 23|2 12.08 5.90 17.98; 9,838 1,475.5| 1,474.51,472.5 . . . . . . . 122.1
12.115 5.90 217.8 |51,785 7,746 || 7,744 |...... 7,738 757.1
12.115 5.90 17.98 9,877 1,481.5| 1,480 1,478 . . . . . . . 122.15
Dec. 1911.5a | 12.065 | . . . . . . 18.00, 3,142G | 1,469 1,468 . . . . . . . . . | 121.85
Dec. 2011.5b | 12.065 | . . . . . . 18.00. 9,799 1,469.5| 1,468.5|. . . . . . tº gº © 121.9
Dec. 22|1.6 2.255 | . . . . . . 18.00. 610 G| 285.3| 284.4|... . . . . . . . . . . 126.3
25.00 705 G| 329.9| 328.9|. . . . . . . . . . . . . . 146.25
1906
May 281.7 2.901 8.64 | 18.00 2,600 381.5| 380.9| 368.4! . . . . . . . 127.15
2.905 7.30 304.6 |14,515 2,120.5| 2,115 |. . . . . . . 2,092 |1,028
2.905 7.30 | 18.00 2,624 384.9| 381.3| 370.8 . . . . . . . 127.8
May 291.8 2.855 15.18 || 18.00, 2,632 386.0| 385.4 363.1] . . . . . . . 127.35
2.856 13.13 |305.0 [14,300 2,088.5: 2,083 |......| 2,075 |1,038
2.856 13.13 | 18.00. 2,658 390.0| 386.4| 367.3| . . . . . . 128.8
June 301.9 || 14.295 26.30 | 18.00|11,420 1,745.5; 1,745 |1,737 . . . . . . 121.65
14.295 25.95 |304.4 |61,020 9,287 9,282 . . . . . . 9,253 922.5
14.295 25.95 | 18.00|11,450 1,750.5. 1,747 1,739 | . . . . . . 121.8
July 51.10 || 43.45 43.83 | 18.00, 3,759 5,048 5,047 |5,042 | . . . . . . 116.15
43.45 43.34 305.5 |18,930 |25,265 (25,260 |......|25,215 827.5
43.45 43.34 | 18.00 3,764 5,056 || 5,052 (5,047 | . . . . . . 116.3
TABLE 5.—Conductivity data on sodium acetate.
Ex- || Milli-equivalents | Tem- Specific conductance X 100. Us
peri- per kilogram. pera- Conduct- Equiva-
Date. ment ture lance X100.| Uncor- e Corrected for #:
* |cHacoanal checoghl “”. * | *|HCahºo, ºn e
1906
June 211.1 2.848 8.82 | 18.00) 1,530.5 234.8] 234.2. 214.2 . . . . . . . 75.3
2.848 7.46 |304.5 (10,505 1,604.5| 1,599 |......] 1,586 794.
2.848 7.46 | 18.00) 1,534.5 235.4] 231.8. 214.9| . . . . . . . 75.55
June 22|1.2 2.810 || 14.46 | 18.00. 1,607.5 246.6] 246.0 213.0} . . . . . . 75.9
2.810 | 11.57 |304.5 |10,355 1,581.5| 1,576.5|. . . . . . 1,569 797
e 2.810 | 11.57 | 18.00. 1,605.5 246.3] 242,7| 216.3| . . . 77.1
July 11.3 || 14.15 23.30 | 18.00| 6,671 1,019.5; 1,018.5|1,007.5 ......] 71.3
14.15 21.99 |304.8 |45,700 6,955 6,950 |......| 6,929 698.5
14.15 21.99 || 18.00; 6,666 1,019 || 1,015 1,004.5 . . . . . . 71.1
July 3|1.4 || 42.49 47.67 | 18.00) 2,123 2,851 2,850 |2,842 | . . . . . . 66.85
42.49 45.29 |304.6 |13,685 18,265 [18,260 |......|18,230 608.5
42.49 45.29 | 18.00. 2,122.5| 2,851 || 2,847 2,840 | . . . . . . . . 66.8


Section 8.-The Conductivity Data. 27
TABLE 6–Conductivity data on ammonium hydroxide.
º Milli- Specific conductance Equivalent con-
*****lequivalents|Tempera- || Conduct- X 106. ductance.
Date. º * | . per ture to. ance X 10" Un- Un-
º kilogram. corrected. Corrected. corrected. Corrected.
1905
Feb. 21...I 18. 99.9 17.95 || 2,067 3.10.2 309.7 3.111 3.106
Feb. 25...] 1b. 99.9 17.95 2,066.5 310.1 309.6 3.110 3.105
Apr. 14...] 2a 103.45 17.95 2,104.5 315.3 314.6 3.055 3.048
216.9 3,047 455.2 452.7 | . . . . . . . . . . . .
17.95 2,065.5 309.5 308.2 | . . . . . . . . . . . . .
Apr. 15...] 2b 103.45 17.95 2,104 315.2 314.5 3.054 3.047
216.9 3,078 459.9 457.4 . . . . . . . . . . . . .
17.95 2,067.5 309.8 308.5 . . . . . . tº de C G D
Apr. 18...] 2C 103.45 17.95 || 2,105 315.3 314.6 3.055 3.048
217.1 3,105 464.0 461.5 ! . . . . . . . . . . . . .
17.95 || 2,068 309.9 308.6 | . . . . . . . . . . . . .
217.1 3,106 464.1 461.6 | . . . . . . . . . . . . º
17.95 2,055 307.9 306.6 | . . . . . . . . . . . . .
217.6 3,094 462.3 459.8 | . . . . . . . . . . . . .
17.95 || 2,049.5 307.1 305.8 . . . . . . . . . . . . .
Apr. 21...] 2d 103.45 17.95 2,104.5 3.15.3 314.6 3.055 3.048
216.5 3,087 461.3 458.8 . . . . . . . . . . . . .
17.95 || 2,078 311.4 310.1 ! . . . . . . . . . . . . .
June 8...! 3 89.6 17.95 | 1,964.5 294.3 293. 6 3.292 3.284
June 10... 4 94.05 17.95 || 2,009.5 301.0 300.5 3.208 3.203
92.9 217.3 2,889 431.6 429.1 5. 520 5.488
92.9 17.95 1,992.5 308. 5 297.2 3.220 3.206
June 17...] 5a 106.85 17.95 || 2,140 320.6 320.0 3.008 3.002
105.8 217.7 3,067 458.3 455.8 5.151 5. 122
p 105.8 17.95 2,117 317.3 316.0 3.006 2,994
June 19...] 5b 106.85 17.95 2,139 320.4 319.8 3.006 3.000
June 20...|*5C 106.85 17.95 2,137 320.1 319.5 3.003 | *2.997
105.35 217.7 3,078 460.0 45.7. 5 5.136 5.108
105.35 17.95 || 2,110 316.1 314.8 3.007 2.995
June 21... *5d 106.85 17.95 || 2,140 320.6 320.0 3.008 || *3.002
105.6 217.4 3,081 460.3 457.8 5.125 5.097
105.6 17.95 2,108.5 316.0 314.7 2.998 2.986
June 25...| 6 85.95 17.95 1,923 288.0 287.2 3.358 3.349
June 30...] 6.1 9.35 17.95 627.4 94.0 93.1 : 10.06 9.97
- 8.965. 217.7 952.5 142.3 139.8 | 18.83 18.49
8.965|| 17.95 618.7 92.7 91.4 || 10.35 10.21
July 4...] 6.2 10.17 17.95 652.1 97.7 97.2 9.52 9. 57
9,785 217. 5 969, 5 144.9 142.4 17. 55 17.25
9.785| 17.95 637.9 95.6 94.3 9.78 9.65
July 21... 7a 89.9 17.95 629.9 G| 294.6 294.1 3.283 3.278
July 21...}*7b. 89.9 17.95 | 1,963 294.4 293.9 3.280 | *3.275
88.9 217.4 2,846 425.7 423.2 5.617 5. 583
88.9 17.95 | 1,933.5. 290.1 288.8 3.269 3.255
Oct. 17...| 8 146.45 17.95 799.6 G. 373.9 373.2 2. 560 2. 555
Nov. 3... 9 134. 55 17.95 767. 1 G| 358.8 358.1 2.673 2.668
134. 55 24.97 893.6 G|| 418.0 417.2 3.119 3.113
Nov. 4...] 9.1a | 10.51 17.95 660.6 99.1 98.6 9.45 9.40
NOV. 5...] 9.1b 10.51 17.95 662.2 99.3 98.8 9. 47 9.42
9.7.15| 218.0 934 139.7 137.2 17.06 16.76
9.7.15| 17.95 631.0 94.7 93.4 9.75 9.62
Nov. 7...] 9.2 12.705] 17.95 730.5 109.6 109.1 8.63 8.59
12.165| 217.2 1,072 160.4 157.9 15.63 15.39
12.165|| 17.95 713.6 107.1 105.8 8.82 8.71

*33.5, 38, and 38 c.cm, of vapor space respectively in experiments 5c, 5d, and 7b.
28 The Hydrolysis of Ammonium Acetate, Etc.
TABLE 6.—Conductivity data on ammonium hydroxide.-Continued.
& Milli- *Specific conductance Equivalent con-
Date º equivalents | Tempera- Conduct- X 106 ductance.
g No. ... per ture zo. ance X 10°. Un- Un-
kilogram. corrected. Corrected. corrected. Corrected.
1905
NOW. 9...] 9.3 12. 645; 17.95 730.0 109.6 109.0 8.68 8.63
10. 97 || 217. 5 1,032 154.4 151.9 | 16.69 16.41
10. 97 17.95 692.9 104.0 102.7 9, 49 9.37
NOW. 11... 9.4 13. 635| 17. 95 759.5 114.0 113.4 8.38 8.33
12.36 217.7 1,069.5 160.0 157.5 | 15.35 15.11
12.36 17.95 718.4 107.8 106.5 8. 74 8.63
1906
Feb. 3... | 10a 147. 55 18.00 2,511 375. 5 374, 9 2.551 2.547
134.1 301.8 1,054 156.7 150.2 1. 671 1.601
134.1 18.00 2,440 364.6 361.0 2.725 2.698
Feb. 5...|†10b 147. 55 18.00 2,513 375. 5 374.8 2.551 f2.546
137.15 || 301.0 1,041.5 154.9 148.3 1.612 1.544
137.15 18.00 2,368 353. 5 349.9 2.584 2, 557
Feb. 6... ::10C 147. 55 18.00 2,501 375.0 374.4 2. 548 2.544
126.35 | 301.8 985. 5 146.3 139.7 1.809 £1.728
126.35 18.00 2,315 346.9 343.3 2.752 2. 723
Feb. 7... ;10d 147. 55 18.00 2,506 375. 5 374.8 2.551 $2.546
97.2 301.9 858. 5 127.4 120.8 2.065 | #1.959
97.2 18.00 2,094 313. 5 309.9 3.232 3,195
Feb. 9... [$10e 14.7. 55 18.00 2,516 375.0 374.4 2. 548 2. 544
147. 55 25.00 2,927 436.3 435. 5 2.969 || $2.963
98.1 301.8 905 134.2 127. 6 1.958 1.862
98.1 25.00 2,411 359. 1 355.5 3.673 3. 636
Feb. 20... 11 522.8 18.00 || 4,528 674. 3 673. 6 1,297 1.295
Mar. 9... 12 512.9 18.00 || 4,574 671.4 670. 6 1. 316 1.315
462.2 301.1 1,922 280. 9 274.3 0.879 0.859
462.2 18.00 || 4,296 630.6 627.0 1.371 1.363
May 23... 13a. 420.9 18.00 || 4,171 612.8 611.9 1,463 1.461
416.2 305.7 1,609 235.4 228.8 0.826 0.803
416.2 18.00 4,100 602.4 598.8 1.454 1.445
May 23... 13b 420. 9 18.00 4,174 613.2 612.3 1.464 1.462
416.8 305.3 1,650 241.4 234.8 0.845 0.822
416.8 18.00 || 4,103 602.8 599.2 1.453 1.444
May 25...} 13C 420. 9 18.00 4,183 614.5 613.6 1. 467 1.465
413.8 305.0 1,670.5 244.3 237.7 0.859 0.836
413.8 18.00 || 4,099 602.2 598.6 1.462 1.453
May 26...| 13.1a; 145.2 18.00 2,525 370.9 370.2 2. 561 2.556
138.8 305.0 972. 5 142.3 135.7 1.479 1.411
138.8 18.00 || 2,449 359.7 356.1 2. 598 2. 571
May 27... 13.1b. 145.2 18.00 2,518 370.0 369.3 2.554 2.549
138.0 304.8 974 142.5 135.9 1. 488 1.420
138.0 18.00 2,451 360.1 356. 5 2. 616 2. 590

fExperiment 10b was rejected, since, the heating was much shorter than in
ments, and its
f46 and 50
and
results show considerable deviation from the others.
c.c.m. of vapor space respectively in experiments 10c and 10d.
{1}, air was boiled out of the solution after the initial measurements in
Č.
the other experi-
experiments 10d
Section 8–The Conductivity Data. 29
TABLE 7–Conductivity data on acetic acid.

* illi- Specific conductance lequivalent conductance.
Date. *:::::: *m. Tempera- Conductance X 106. quiv conductanc
No. ... per ture tº. X 106. Un- Un-
kilogram. corrected. Corrected. corrected. Corrected.
1905
July 14...| 1 91.35 17.95 961 G| 449.5 448.9 4.924 4.917
July 17...| 2 109.1 17.95 | 1,046 G| 489.2 488.6 4.487 4.481
July 18...| 3a. 97.5 17.95 989. 5 G| 462.9 462.2 4.751 4.744
.5
Aug. 11...] 3b 97.5 17.95 || 3,080.5 462.0 || 461.3 4.741 || 4.734
97.0 217.8 2,935.5 439.1 || 436.6 5.370 5.340
97.0 17.95 3,059 458.7 457.5 4.731 || 4.719
Aug. 13... 3C 97.5 17.95 || 3,077 461.4 460.7 || 4.735 || 4.728
96.95 217.5 2,946 440.7 || 438.2 || 5.391 || 5.361
96.95 || 17.95 3,065 459, 7 || 458.4 4.744 4.730
Oct. 10... 4 209.9 17.95 || 1,453 G| 679.4 678.6 3.235 | 3.231
*May 5... 5.1a | 143.5 18.00 3,837 563.6 562.7 3.928 3.921
144.45 304.6 1,178.5 172.4 | 165.8 | 1.712 | 1.646
e 144.45 18.00 3,793 557.3 || 553.7 || 3.858 || 3.833
*May 7...] 5.1b 143.5 18.00 3,835 563.4 562.5 || 3.926 3.920
144.15 305.1 | 1,148 167.95, 161.3 | 1. 673 1.607
144.15 | 18.00 3,788 556.5 552.9 || 3.869 ; 3.844
May 8... 5.1c 143.5 18.00 || 3,833 563. 1 || 562.2 || 3.924 || 3.918
142.7 305.3 | 1,122.5 164.2 157.6 | 1.651 | 1.585
142.7 18.00 3,782 555.6 || 552.0 3.894 || 3.868
May 13...| 6a 432.5 18.00 6,490 953. 5 || 953 2.200 || 2, 198
431.3 || 305.1 | 1,792 262. 1 || 255.5 || 0.873 || 0.851
431.3 18.00 | 6,363 935 931.5 2.163 || 2,154
May 15... 6b 432, 5 18.00 | 6,489 953.5 953 2.199 || 2, 198
431.2 : 306.0 | 1,768 258.6 || 252.0 0.864 0.842
431.2 18.00 | 6,368 935. 5 || 932 2.165 2. 156
May 18... f6C 432.5 18.00 6,464 954 953.5 2.201 || 2.200
431.3 304.9 1,787.5 261.5 || 254.9 || 0.893 0.871
431.3 18.00 6,353 937. 5 || 934 2.169 || 2. 160
May 20...f6d 432.5 18.00 6,458 953 952.5 2, 199 || 2.197
430.8 || 305.1 | 1,783.5 260.9 || 254.3 || 0.895 || 0.872
430.8 18.00 6,342 936 932.5 2.168 2. 159
|
º fºrgiments 5.la and 5.1b the solution was boiled for a few minutes after the measure-
IIle11t a •.
f39 and 42 c.cm. of vapor space in experiments 6c and 6d respectively.
30
The Hydrolysis of Ammonium Acetate, Etc.
TABLE 8.—Conductivity data on ammonium acetate.

Date.
Experi-
Inent
No.
Specific conductance
X 106.
Per-
centage
change
at 18°.
1905
July 29..
Aug. 2..
Oct. 18.
Oct. 19.
Oct. 21..
Oct. 22.
Oct. 23.
Oct. 24.
Oct. 26.
Oct. 27..
Oct. 28.,
Oct. 30..
Oct. 31..
NOV. 1..
Nov. 24.
Nov. 25.
Nov. 26..
NOV. 27..
Nov. 28.
;
:
Milli-equivalents per kilogram.
NH4C2H3O2
NH4OH
HC2H3O2
Temi-
pera-
ture tº.
Con-
ductance
X 106
Un-
corrected.
Corrected
for
impurities.
*2.3a.
.3b
14. 595
14.46
14.03
7. 11
7.18
7. 18
7.15
7. 15
7.15
7, 15
7.13
14.24
14.125
14.155
7. 12
7.055
7.20
7.235
7.11
7.19
7. 19
7.41
7,41
13.97
13.97
28.02
14.32
27.75
55.43
7.09
14.29
28.61
17.95
17.95
17.95
217.8
17.95
17.95
217.9
17.95
17.95
217. 5
17.95
17.95
217.6
17.95
17.95
217.8
17.95
17.95
217.8
17.95
17.95
218.0
17.95
17.95
217.9
17.95
17.95
218.1
.95
.95
218.2
.95
.95
217.8
. 95
.95
217. 9
17.95
17.98
217. 5
17.98
17.98
217.3
17.98
18.00
217.3
18.00
18.00
217.9
18.00
18.00
218.1
18.00
8,738
8,678
8,439
25,280
8,420
4,373
12,875
4,328
4,462
17,270
4,529
4,461
16,905
4,585
4,464
17,210
4,446
4,470
17,205
4,477
4,478
19,285
4,476
4,477
19,215
4,473
4,532
21,130
4,541
8,625
33,495
8,635
8,593
36,775
8,599
8,679
40,865
8,642
4,383
13,095
4,401
4,343
12,960
4,350
4,505
17,570
4,513
4,568
19,760
4,572
4,585
21,515
4,574
1,310.5
1,301.5
1,265.5
3,781
1,262.5
655.7
1,925.5
649.1
669.2
2,583
679.2
669. 0
2,529
687.6
669.4
2,574
666.7
670.3
2,574
671.3
,670.8
2,885
671.2
671.4
2,874
670.7
679.6
3,161
681.1
1,293. 5
5,010
1,295
1,288.5
5,501
1,289.5
1,301.5
6,113
1,296
657.3
1,958.5
660.0
651.3
1,938.5
652.4
675.7
2,628
676.8
685.1
2,956
685.7
687.6
3,219
685.9
1,310
1,300.5
1,264.5
3,779
1,261
655.1
1,923
647.8
668.5
2,580
677.9
668.3
2,526
686.3
668.6
2,572
665.4
669 - 5
2,571
670.0
670.3
2,882
669.9
670. 9
2,872
669.4
679.0
3,158
679.8
1,292.5
5,007
1,293.5
1,287.5
5,498
1,288
1,300.5
6,110
1,294.5
656.7
1,956
658.7
650.7
1,936
651.1
674.8
2,626
675. 5
684.2
2,953
684.4
687.0
3,216
684.6
*Experiments 2.3a and 2.3b were rejected, since, the final conductance shows that some acci-
dental contamination of the solution has occurred.
"Sieu]O 9
uo.JJ uoneſ Aap opia Sqn Jo asneoaq ‘pagoaſon sea qualujiadka Sºu, Luo Ig e208 qa 4Insor #. l{}
0 °OT- 898'8 2.98°g | 080°33 |OO'8T 6' g2[] * * * * * * II* 68
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tº e º e e #0g'3 OIg°3 || gli'9T | 1. ‘jog ' ' ' ' ' ' | * * * * * #1," Iy |0% ‘8 |“gg ounſ
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6° 3– 189'8 I6ç“g | 01:#"gg|00°8T | * * * * * * * * * * * * 62. ‘If
tº G e º o #Ig": 0.39% | 0%g'9T | 8" FOg| * * * * * * * * * * * 6A," Tj,
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& Cº - © º e £39"I g’938°I #20°6 |00°8T | * * * * * * | 68" &#| gT3";1 |883’ & ‘‘3 9UInſ
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g" g—| I93*I | g "#83“I gº,"8 |00 '81 36°37 |* * * * * * g/0"?I
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g"I- 963"I g’662*I 9%’8 |00°8T g/.3°7'I |* * * * * * 903**I
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• * * * * *| 698°g 32.8'g | 988'gz 6'913
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32 The Hydrolysis of Ammonium, Acetate, Etc.
9. EQUIVALENT CONDUCTANCE VALUES AT ROUND TEMPERATURES.
The next step in the further reduction of the data to comparable values
is their correction to round temperatures. Temperature-coefficients at
18°, 218°, and 306° were obtained by plotting against the temperature
the conductances given in the preceding tables after correcting them
approximately to round concentrations. Thus the correction to round
temperatures was made on the conductance alone, none being required
on the concentration. In the case of ammonium hydroxide, the data
obtained at 302°, before the use of diphenylamine as a heating substance
was abandoned, permitted a more accurate calculation of the temperature-
coefficient than could be obtained for 306” by drawing the curve through
156”, 218°, and 306°. Yet, since the correction to round temperatures
was seldom more than 2 per cent, the coefficient does not need to be
very accurately known.
In table 9 are given the temperature-coefficients employed, expressed
in per cent of the equivalent conductance at the temperature in question
for the first four substances, and in per cent of the specific conductance
for ammonium acetate.
TABLE 9.—Temperature-coefficients of conductance.

Milli-
Substance. equivalents 189. 2189. 306°.
per liter.
NH,Cl . . . . . . . . . . . . . . 30 2.20 | . . . . . . 0.16
10 2.20 0.36 0.21
2 2.20 0.37 0.26
NaCaFis02 . . . . . . . . . . . 30 . . . . . . . . . . . . . 0.20
10 ! . . . . . . . . . . . . . 0.25
2 | . . . . . . . . . . . . . 0.32
NH4OH . . . . . . . . . . . . . 300 | . . . . . . . . . . . . . —2.65
100 2.38 —0.78 || —3.95
10 2.15 —0.66 | . . . . . .
HC2H2O2 . . . . . . . . . . . . 300 . . . . . . . . . . . . . —2.0
100 1.70 | —0.77 | —3.0
NH4C2H2O, G e º º ſº e & G s sº 30 ſº tº G & © tº & º ºs & tº —3 o 15
10 2.75 | –0.85 | —3.35
1 NH,C,EIAO, + } 30 e e º E U Gº || - º O sº º º —2 ſº 8
1 NH4OH or 1 HC, H2O, 10 2.75 —0. 82 | —2.95
1 NH,C,EI2O, + } 30 tº e º & © e tº e º ſº e ſº —2 ſº 3
3 NH,OH Or 3 HC, HaO, 10 2 e 75 —0 © 77 —2 o 4
In table 10 are given the conductance values for ammonium chloride.
The first column gives the number of the experiment, corresponding to
that in the table of Conductivity Data. The next three columns give the
concentration in milli-equivalents per liter of solution, calculated as
described in section 6. The fifth column shows the ratio, in equivalents,
Section 9.-Summary of Equivalent Conductances. 33
of the ammonium hydroxide to the ammonium chloride present, the excess
of base having been added in the experiments carried to the higher
temperature in order to reduce the hydrolysis nearly to zero. The next
three columns give the equivalent conductance at 18° before and after
heating to 218° or 306°, and that at 218° or 306°. The increase of con-
ductance at 18” shows that a slight contamination occurred. This has
been corrected for in the last column by diminishing the conductance at
218° or 306” by one-half of the percentage increase at 18°. This correc-
tion is about 0.1 per cent, except in Nos. 1.2b and 1.8 where it is 0.5 per
cent; the results of these experiments are therefore given a weight of
one-half.
In table 11 are given in a similar manner the results with sodium acetate.
TABLE 10.-Equivalent conductance of ammonium chloride at round temperatures.

ſº Milli-equivalents of salt per liter. Ratio of Equivalent conductance.
Experi- NH4OH * O
** | 18° initial. 18° final. 218° tº Näää. 18°initial. 18° final. 218° e.g.
1.5a. 12.05 Q @ º O O C T C tº Q @ e e 0 121.85 . . . . . . tº dº tº a tº º 'º C Q @ C.
1.5b 12.05 © Q Q g º O || @ ſº G & © tº 0 121.9 Q: º g º ºs e tº gº e © º ſº I º e º g º ºs
1.1 10.885 Q & © tº º º C tº gº tº º º 0 122.2 © 2 g g º e º a C Q Q I gº º O ſº ſº º
1.6 2.252 Q Q & Q @ Q || > ºn º º ſº º 0 126.3 Q & C & © tº ſº ſº e Q & G | Q & Q & G tº
2.0 12.065 12.10 10.22 0.49 122.15 122.2 757.6 757.4
1.4 10.015 10,045 8.48 0, 60 122.85 | 123.05 765.4 764.6
1.2a. 2.356 * > & © ſº e º G & © tº Gº tº 0.51 126.85 . . . . . . . . . . . . . . . . . . . .
1.2b 2.356 2.363 1.995 0. 51 126.9 128.15 802.3 798.3
1.3a 2.238 2.245 1.894 0.54 126.8 126.9 802.2 801.8
1.3b 2.238 2.245 1.895 0. 54 127.25 | 127.35 804.1 803.7
306°. 306°. 306° cor.
1.10 43.41 43.41 30.48 1.00 116.15 || 116.3 828 827.5
1.9 14.275 14.275 || 10.03 1.82 121.65 121.8 925.5 925
1.7 2,897 2.901 2.035 2.51 127.15 127.8 1,032 1,029.5
1.8 2.851 2.852 1.999 4.60 127.35 | 128.8 1,040.5 | 1,034.5
25°. 259,
1.1 10.87 tº º e º ſº º º e O 141.35 | . . . . . . . . . . . . . . . . . . . .
1.6 2.249 © Q & Q & © C tº dº tº gº tº 0 146-25 | . . . . . . . . . . . . . . . . . . . .
TABLE 11–Equivalent conductance of sodium acetate at
round temperatures.

Milli-equivalents of Ratio of Equivalent conductance.
Experi- salt per liter. HC2H8O2 a
ment No. Hz sº to Nachaos. 18°initial. 18° final. 306°.
1.4 42. 52 29.95 1.07 66.85 | 66.8 || 613
1.3 14.13 || 9.92 1.56 71.3 || 71.1 || 702.5
1.1 2.844 | 1.998 2.62 75.3 75.55 | 800
1.2 2,806 | 1.9685| 4.11 75.9 77.1 803
It will be seen that the conductances at 18° of the first four ammonium
chloride solutions containing no excess of ammonia are uniformly about
0.3 per cent lower than those of the solutions containing ammonia. The
34 The Hydrolysis of Ammonium Acetate, Etc.
cause of this small difference is not known; but it may be due to a slight
contamination by carbon dioxide. It may also be mentioned that, when
corrected to the same concentration, the conductance of ammonium
chloride solution No. 2 which was made from standardized hydrochloric
acid and ammonia, agrees almost exactly with that of the other entirely
independent solutions made from the stock solution of the crystallized salt.
In tables 12 and 13 are presented in a similar manner the equivalent
conductances of acetic acid and ammonium hydroxide corrected for the
impurities in the water and reduced to round temperatures. Two columns
are, however, added in which are given the ionization-constants KB or KA
for these substances calculated directly from the separate values of the
{º º A2C
equivalent conductance by the equation (A, - A) A,Ao – A)Ao
this furnishes the best means of showing the agreement of the results
of the different measurements. The Ao values employed are those derived
and tabulated in section 10. In the case of the experiments with ammo-
nium hydroxide, solutions 1, 2, 3, 6, and 12 were prepared from Baker
and Adamson's purest aqua-ammonia, the others from liquid ammonia,
as described in section 4.
= KB or KA; for
º
TABLE 12.-Equivalent conductance and ionization-constant of acetic acid at round

temperatures.
Experi- Milli-equivalents per liter. Equivalent conductance. KA X 109
ment No. 180 initial. 189 final. 218° | 18° initial. 18° final. 218° 18°. 218°
4 || 210.0 … [… 3.234 . . . . . . . . . . . . . . 18.30 l. . . . . .
2 109.05 tº e º O ſº ºn tº e o ſº gº ºn 4.484 Q & Q & © Q º O ſº ºn tº º 18.33 |. . . . . .
3a. 97.45 & Q - is ſº º gº tº c e 4. 747 & J & J C → tº Q & Q * 18.37 Q & Q & G C.
1. 91.3 ſº tº ſº tº gº tº tº e º O ſº º 4.920 C & C & G → © Q & Q & 18.50 Q Q & Q Q Q
3b 97.45 96.95 81.75 4.737 4.722 5.332 18.29 |1.720
3C 97.45 96.9 81.75 4.731 4. 733 5.340 18.25 (1.725
Mean gº tº ſº gº º tº e º e a e º e º e º ſº e º e e c Q & © tº 9 tº i e o e º e G *18.34 |1.723
| 3060 3069 306?
63. 433.5 432.3 300.4 2. 198 2. 154 0.836 17.39 |0. 1305
6b 433.5 432.2 299.2 2. 198 2. 156 0.843 17.39 (0.1325
6C 433.5 .432.3 292.7 2.200 2. 160 0.852 17.42 |0,132
66. 433.5 431.8 291.5 2.197 2. 159 0.857 17.38 |0. 1335
Mean tº gº & © tº e i º º e º ºs e : C tº e e º e e º e º 'º e ] e º 'º e º ºs tº g tº G & © 17.40 (0.132
5.1a | 143.5 144.45 100.75 3.921 3. 833 1.577 18, 41 |0.156
5.1b | 143.5 144.15 |100.4 3.920 3.844 1.563 18.40 |0,153
5.1C 143.5 142.7 99.45 3.918 3.868 1. 552 18.38 0.149
Mean tº º º º o © o º tº tº gº ºn tº gº ſº * > * > & Cº. º. C & © tº e C © C C C C & *18.40 0.153
*The mean of all the values at 18° for the concentrations between 210 and 91 milli-normal
is 18.36.
Section 9–Summary of Equivalent Conductances.
35
TABLE 13–Equivalent conductance and ionization-constant of ammonium hydroxide
m at round temperatures.

Experi- Milli-equivalents per liter. Equivalent conductance. 1 KB X 106
*** | 18° initial. 18° final. 218° 18° initial. 18° final. 218° 189 218°
Ža. 103.2 © C C C & Gº || C C C C C & 3.051 © Q & C G tº gº ºn tº e º e 17.13 ſ. . . . . .
2b 103.2 C & © tº dº e º C G & 3.050 tº Q & Q & Q , © tº e º ºs 17.11 I. . . . . .
2C 103.2 * tº _º e e s e e 3.051 tº G → Q, Q tº gº e - © tº 17.13 . . . . . .
2d 103.2 | . . . . . . . . . . . . . 3.050 © º O ſº º tº - e º e º © 17.11 tº e º 'º e
1a 99.7 0 s tº e s as I e º 'º 1 º' 3.109 C C C C C & e º e o e ſº 17.18 l. . . . . .
1b 99.7 tº ſº C G G - || @ tº º º ºs e 3.108 © & © tº º tº e º e º e e 17.17 l. . . . . .
3 89.4 Q & Q (- - © & & © e º 3.287 © & © e e º e º e º e o 17.24 |. . . . . .
6 85.75 tº & Cº is is º tº e º e º ſº 3.352 Q & C tº ... ... 17.20 l......
Mean | . . . . . . tº C C tº G | C C C C C º tº e º ſº e - & © & © tº º ſº tº e º gº º 17.16 |. . . . . .
5b 106.6 tº ſº g º 'º e º O & © e º 'º 3.003 tº de G & © tº e º e e º ºs 17.13 l. . . . .
5a. 106.6 105. 55 89.0 3.005 2.997 5.110 17.15 (1.797
50 106.6 105.1 89.55 3.000 2.998 5.096 17.09 1.794
5d. 106, 6 105.35 89, 8 3.005 2,989 5.073 17.15 1.783
4 93.85 92.7 78.2 3.206 3.209 5.458 17.20 (1.798
7a. 89.75 | . . . . . . © e o e º O 3.281 © & ſº tº º tº e º O O 17.23 l. . . . . .
7b 89.75 88.75 75.8 3.278 3.258 5. 55? 17.20 |1.807
Mean | . . . . . . . . . . . . . & J C & © & J C C C º & © º C G is ſº e º º a 17.16 1.796
9.4 13. 615 12.34 10.42 8.34 8.64 15.08 17.26 1.84
9.2 12,685 12.16 10.26 8.60 8.72 15.31 17.13 1.87
9.3 12.63 10.955 9.255 8.64 9.38 16.36 17.21 (1.93
9. 18. 10.495 * @ Q g º º tº ſº tº J C. 9.41 * & © tº ſº tº tº C C & © tº 17.02 . . . . . .
9.1b 10.495 9.70 8.185 9.43 9.63 16.76 17.09 |1.79
6.2 10. 155 9.77 8.255 9. 58 9.66 17.19 17.08 1.90
6.1 6. 9. 335 8.95 7.56 9.98 10.22 18.44 I7.08 2.00
Mean to ſº o G - © & C tº e Q tº º º ſº G º tº dº º O O © º C G tº ſº º 17.12 1.89
3069 306? 306°
11 520.0 & C L G → Gº || 0 & © O C C, 1.295 | . . . . . . e - e º º º 15.44 I. . . . . .
12 510.1 459.9 3.19.4 1.315 1,363 0.760 15.60 |0.0935
I3b 418.9 414.9 285.7 1.462 1.444 0.807 15.84 |0.0940
13a. 418.9 414.3 285.1 1.461 1.445 0.797 15.82 |0.0915
13C 418.9 411.9 284.4 1.465 1.453 0.814, 15.91 |0.0955
Mean © & Q - tº e G G → g º ſº Q Q @ º gº º © e o e o e e º G & G G e Q e . . . . . . |0.0935
10b 147.2 tº G & © tº gº tº 2.546 | . . . . . . tº º ſº 16.97 | . . . .
8 146.1 © º & C & © e º 'º C L Q. 2.558 | . . . . . . © tº G 17.00 to c > → ~
9 134.25 tº º O J & gº tº ſº ſº tº c 2.671 | . . . . . . G º º ſº º 17.04 I. . . . . .
13.1a | 144.85 138.5 96.2 2.556 2.571 1.357 16.83 |0.0895
13.1b | 144.85 137.65 95.75 2. 549 2. 590 1.356 16.74 |0.0890
10a 147.2 133.8 93.8 2.547 2.698 1.374 16.98 |0.0895
10C 147.2 126.1 80.85 2. 544 2.723 1.483 16.94 (0.0900
10e 147.2 97.75 68. 55 2. 544 *3.636 1.598 16.94 |0.0885
106. 147.2 97.0 61.7 2. 546 3.195 1.681 16.97 |0.0885
Mean & Q tº e º ſº. Q & Q & G T G G & © º * I e g º O e º tº e o e º a e º 'º e & © 16.93 |0.0895
259 250 25°
10e 147.0 tº C ºs tº & © tº e º ºs 2.963 e G & º e º e º & © tº e 17.82 |. . . . . .
9 134.0 G. G. v c e º e º e º 'o c 3.115 . . . . . . . . . . . . 17.96 |. . . . . .
Mean tº º ºp º e ºs & O U º e º Q Q @ e g c || @ G & C G & e ſº e e g º e º e º C G 17.89 |. . . . . .
*This was the conductance at 25°.
36 The Hydrolysis of Ammonium Acetate, Etc.
A comparison of the separate values of the ionization-constants for
nearly the same concentrations in tables 12 and 13 shows at each tem-
perature an entirely satisfactory agreement. Moreover, the mean of
the first series of values for ammonium hydroxide, which were obtained
with solutions prepared from a pure commercial aqua ammonia, will be
seen to be identical with the mean of the second series of values, which
with solutions prepared from a pure commercial aqua ammonia, will be
10. FINAL VALUES OF THE EQUIVALENT CONDUCTANCE AND THEIR
VARIATION WITH THE CONCENTRATION AND TEMPERATURE.
Final values of the equivalent conductance at round concentrations for
ammonium chloride and sodium acetate and for ammonium hydroxide and
acetic acid have been derived from those given in tables 10 to 13.
This has been done in the case of the two salts at 306° with the help
of the function C(Ao — A) = K(CA)" by first determining the values of
the three constants Ao, K, and n, by substituting the values of A at the
three widely different concentrations, and then calculating in the reverse
way the value of A for various round concentrations. In the case of
ammonium chloride at 18° and 218", however, since only two widely
different concentrations were investigated, the value of n was assumed
to be identical with that found for the very analogous salt potassium
chloride, namely 1.42 at 18° and 1.50 at 218". (At 18° and 25° the
measurements with the pure salt, without excess of ammonium hydroxide,
were alone utilized.) The values of A and of Ao so obtained are sum-
marized in Table 14. The values of n at 306° derived as just described
are 1.44 for ammonium chloride and 1.49 for sodium acetate.
In the cases of ammonium hydroxide and acetic acid values for Ao
were first obtained indirectly by the relations:
Ao(NH4OH) = Ao(NH,Cl) +Ao(NaOH) - Ao(NaCl)
Ao(HAc) = Ao(NaAc) +Ao(HCl) - Ao(NaCl)
Most of the Ao-values for the substances on the right were taken from the
various parts of this publication. In the case of sodium hydroxide, how-
ever, no measurements exist at 306°, and those at 218° are not suf-
ficiently accurate nor extensive. Ao-values for it were therefore derived
under the assumption that it lies at such a proportional distance between
the Ao-values for sodium chloride and hydrochloric acid at these tem-
peratures as is indicated by its position between them at the lower
temperatures of 18°, 100°, and 156*. All these Ao-values are given in
the following table. Those for ammonium acetate which are needed in
the subsequent calculation of the hydrolysis of this salt are also included.
They were derived by combination of those for ammonium chloride,
Section Io.—Final Values of the Equivalent Conductance.
sodium acetate, and sodium chloride.
37
The Roman numerals within
parentheses show the Part of the publication,” and the immediately fol-
lowing number, the table, from which the Ao values were taken.

Substance. 189 259 218.9 306°
NH4C1......... 130.9% 152.0 (tab. 14) | 841 (tab. 14) 1,176 (tab. 14)
NaC2H5O2 78.1 (V, 36) tº º C tº º º 660 (V, 36) 924 (tab. 14)
NaOH......... 216.5 (VI, 59) * º 'º º 1,060 1,310
HCl ............ 379 (W, 36) C - e. e. e. e. 1,265 (V, 36) 1,424 (VIII, 109)
NaCl.......... 109.0% . . . . . . 760 (II, 9) 1,080 (II, 9)
NH4OH ...... 238.4 270.6t 1,141 1,406
HC2H5O2 ..... 348.1 Q & © º ſº º 1,165 1,268
NH4C2H5O2. 100.0 e e o ſº 74.1 1,020
*Mean of the results presented in this Part, Table 14, and in Part VI, Table 59.
f Value of Kohlrausch.
#Calculated from the NH4OH value at 18° by
the ions (Sitzungsber. preuss. Akad., 1901, 1031
* of Kohlrausch's temperature-coefficients for
With the help of these Ao-values for the ammonium hydroxide and
CA)
acetic acid the ionization-constants
C (A6 – A) Ao
—e
already given in tables
12 and 13 were calculated; and from the means of these for each near-
lying series of concentrations, the values of A at round concentrations
were obtained by reverse calculation.
table 14.
The latter are summarized in
TABLE 14.—Final values of the equivalent conductance at round
temperatures.
Milli-
Substance. equivalents 18°. 25°. 218°. 306°.
per liter.
Ammonium 30 118.1 ! . . . . . . . . . . . . tº 828
chloride 10 122.5 141.7 758 925
2 126.5 146.5 801 1031
0 131.1 152.0 841 1176
Sodium ace- 30 | . . . . . © e º º tº e Ge e e º 'º o 613
tate 10 & tº e o O e º ſº e º e © e º e tº 702
2 tº Q tº Q & Q I g tº ſº G & C © ſº a º º 801
O to e º O tº tº I º G & © e ſº a & 924
Ammonium || 500 1.325 . . . . . . e J is a e © C C C E &
hydroxide 300 1.752. . . . . . . tº ſº Q tº tº 0.785
100 3. 103 3. 62 4.821 1.329
80 3.466] . . . . . . 5.389. . . . . . .
10 9.66 | . . . . . . 15.56 G C & © C Q
0. 238.4 270.6 1141 1406
Acetic acid 300 . 2.682] . . . . . . © º O C C & 0.841
100 4.685. . . . . . . 4.824 1.567
80 5.234] . . . . . . 5.393! . . . . . .
0 348.1 tº e º 'º e G 1165 1268 {}

*Publication No. 63 of the Carnegie Institution.
38 The Hydrolysis of Ammonium Acetate, Etc.
For the sake of comparison the values obtained by other workers in
this laboratory are here tabulated.

0.002 Normal 0.1 normal NH4OH. 0.08 normal HC2H8O2.
NH4Cl at 18°. at 1so. at 25°. at 18°. at 218°.
Noyes and Cooper. . . . . . . . . . . . . . . . . . . . . 5.22 5.34
Noyes and Kato... 126.6 3.10 ! . . . . . . . . . . . . . . . . . . . .
Kanolt . . . . . . . . . . . . . . . . . . . 3.11 3.61 | . . . . . . . . . . . . .
Sosman . . . . . . . . . . . *126.5 3.10 3.62 5,23 5. 39
*Kohlrausch found 126.2.
It is of interest to consider the change with the temperature of the
Ao-values for ammonium chloride and sodium acetate, taken in combi-
nation with the results of Noyes and Kato (table 59, Part VI) and of
Noyes and Cooper, table 36, Part V). The values of AA/At for the
successive temperature-intervals are given in table 15; and the ratio of
their Ao-values to those of potassium chloride and sodium chloride at
the same temperature are given in table 16.
TABLE 15.-Temperature-coefficients of the equivalent conduct-
ance at gero concentration (AAo/At).

Substance. Ao at 18°. | 18-100°. 100–156°. | 156–218°. 218–306°.
NH,Cl............ 130.9 3.47 3.80 3.43 3.81
NaC2H5O2 ...... 78.1 2.53 2.95 || 3.40 || 3.00
TABLE 16.-Ratio of Ao-values to those for other substances.

Substance. 18°. 100°. 156°. 2.18°. 3069.
NH,Cl: KCl.............. 1.01 | 1.00 | 1.00 | 1.02 | 1.05
NaC2H5O2 : KC1........ 0.60 0.69 || 0.72 || 0.80 || 0.82
NaC2H5O2 : NaCl...... 0.72 0.79 || 0.81 0.87 || 0.86
It will be seen from these tables that the Ao-values for ammonium
chloride increase with the temperature in nearly the same way as do those
for potassium chloride, there being two points of inflexion in the con-
ductance-temperature curve, namely, between 100° and 2.18°, and 2.18° and
306°. For sodium acetate, on the contrary, the rate of increase with the
temperature becomes steadily greater up to 218°. The equivalent conduct-
ance of the acetate ion, however, steadily approaches that of the chloride
ion (except through the interval 218°–306° where the slight decrease in
the ratio for sodium acetate to sodium chloride may be due to error).
Section Io.—Ionization Values. 39
With respect to the change of equivalent conductance with the con-
centration, mention need only be made of the fact that the values of the
exponent n in the function C(Ao — A) = K(CA)” are about the same
for these two salts at 306° as for the other salts previously investigated,
namely, 1.44 for ammonium chloride and 1.49 for sodium acetate. In the
cases of the base and acid the value of n is approximately 2, as the mass-
action law requires (see section 11.) -
The equivalent-conductance values for the base and acid (for example,
at 100 milli-normal) decrease greatly between 218° and 306° and are
less at the latter temperature than at 18°. This arises, of course, from
a greatly decreased ionization, which overcompensates the increased
equivalent conductance of the ions.
IONIZATION VALUES AND THEIR VARIATION WITH THE CON-
CENTRATION AND TEMPERATURE.
| 1.
Table 17 contains the percentage ionization-values for the four sub-
stances whose equivalent conductances were given in table 14. The
values are simply those of the ratios 100A/Ao.
TABLE 17.-Percentage ionization.

Milli-
Substance. equivalents | 18°. 259. 218°. 306°,
per liter.
Ammonium 30 90.1 ! . . . . . . . . . . . . . 70.4
chloride 10 93.5 93.2 90.1 |78.7
2 96.5 96.4 95.3 |87.7
Sodium 30 | . . . . . . . . . . . . . . . . . . . . 66.4
acetate 10 ! . . . . . . . . . . . . . . . . . . . . 76.0
2 . . . . . . . . . . . . . . . . . . . . 86.7
Ammonium 500 0.556! . . . . . . . . . . . . . . . . . . .
hydroxideſ 300 0.735i . . . . . . . . . . . . . 0.0558
100 1.302| 1.338|| 0.422 0.095
80 1.454! . . . . . . 0.472. . . . . . .
tº 10 4.05 ! . . . . . . 1.36 . . . . . .
Acetic acid 300 0.771] . . . . . . . . . . . . . 0.0663
100 1.346] . . . . . . 0.414| 0.124
80 1.504! . . . . . . 0.463] . . . . . .
The ionization values for ammonium chloride and sodium acetate even
at 306° are only slightly less than those for sodium and potassium chlo-
rides, for which in 10 milli-normal solution the values 79.6 and 81.2 per
cent were found by Noyes and Coolidge (see table 12, Part II). The
ionization of both ammonium hydroxide and acetic acid is seen to have
become very much less at the higher temperatures. The separate values
of their ionization-constants have already been given in tables 12 and 13.
40 The Hydrolysis of Ammonium Acetate, Etc.
In table 18 are given the means of these for each group of nearly equal
concentrations, which means correspond to the ionization values given in
table 17. In computing these constants the concentration has been
expressed in equivalents per liter. In the last line under each substance
are given in black type, what are probably the best values for dilute solu-
tions, taking into consideration the experimental errors in the more dilute
solutions and the deviation from the mass-action law in the more con-
centrated ones.
TABLE 18.-Ionization-constants X 106 for ammonium
hydroxide and acetic acid.

Substance. º 18°. 25°. 218°. 306°
Ammonium! 0. 52 15.5 |. . . . . . . . . . . . . . . . . .
hydroxide 0.42 15.9 |. . . . . . . . . . . . . . . . . .
0.30 l. . . . . . . . . . . . . . . . . . 0.094
0.15 16.9 17.9 |. . . . . . . . . . . .
0.10 17.2 |. . . . . . 1.80 0.090
0.01 17.1 |. . . . . . 1.89 |. . . . . .
Best Value | 17.2 | 18.1 | 1.80 || 0.093
Acetic acid 0.43 17.4 . . . . . . . . . . . . . . . . . .
0.30 | . . . . . . . . . . . . . . . . . . 0.132
0.14 18.4 . . . . . . . . . . . . . . . . . .
0.10 18.3 . . . . . . 1.72 0.153
Best Value | 18.3 . . . . . . 1.72 || 0.189
It will be noted that at 18° the ionization constants of both substances
are considerably less at 0.4 normal than at 0.1 normal, doubtless because
of inaccuracy in the assumptions involved — the validity of the mass-
action law or the proportionality between ionization and equivalent con-
ductance. That at the higher temperatures of 2.18° and 306° the mass-
action law holds, at any rate approximately, at moderate concentrations
is shown for ammonium hydroxide by these results. This has previously
been shown to be true for acetic acid at 218” by Noyes and Cooper.
Their values of the constant (18.2 and 1.69 × 10−") also agree well with
mine (18.4 and 1.72 × 10−"). This is especially true when the somewhat
different manner of correcting for the conductance of the water is con-
sidered; thus their value at 218° when corrected as described in section
5 of this Part becomes 1.72. º
Section I2.-Hydrolysis of Ammonium Acetate. 4I
12. HYDROLYSIS OF AMMONIUM ACETATE AND IONIZATION OF
WATER AT 2.18° AND 306°.
In order to derive the degree of hydrolysis of ammonium acetate, the
specific-conductance values given in table 8 have been first corrected
to round temperatures by means of the temperature-coefficients given in
table 9, and the content by weight has been reduced in the usual way to
volume-concentration at the temperature of the measurement. These
conductance values were previously corrected for the conductance of the
impurities in the water; and a correction has now been applied for
that of the ionized water, or of the base or acid added, in those cases where
the correction exceeds 0.1 per cent. This correction was calculated from the
ionization-constants for these substances and the equivalent conductance
of the ions, as described in section 5. In no case did the correction
exceed 0.25 per cent. -
Table i9 contains the so-corrected data for the pure salt, and table
20 those for the salt with an excess of base or acid. In the latter table
are given for 218° and 306° in two additional columns (1) the specific
conductance (Lo) which the pure salt has at the same concentration as
that (C) of the salt in the mixture, and (2) the ratio of the specific con-
ductance (L) of the salt in the mixture to this conductance Lo. The
specific conductance Lo is calculated from that given in table 19 for
nearly the same concentration under the assumption of proportionality
between conductance and concentration through the small interval
involved.
TABLE 19–Specific conductance at round temperatures of
pure ammonium acetate solutions.

Experi- Milli-equivalents per liter. Specific conductance X 106.
ment No. 180. 2.18°. 306°. 18°. 2.18°. 306°.
1.3 14.57 | . . . . . . . . . . . . . 1,311.5 . . . . . . . . . . . . tº
1.4 14.44 | . . . . . . . . . . . . . 1,302 | . . . . . . . . . . . . ©
2.1 14.01 11.81 | . . . . . . 1,266 3,770 | . . . . . .
2.15 14.18 12.01 . . . . . . . 1,281.5 ! 3,830 | . . . . . .
Meart - 14.30 | 11.91 | . . . . . . 1,290 3,800 | . . . . . .
2.2 7.10 5.93 + . . . . . . 656.0 | 1,918.5 | . . . . . .
2.10 7.11 6.025 | . . . . . . 657.0 | 1,944.5 | . . . . . .
2.11 7.045 || 5.96 | . . . . . . 651.0 | 1,921.5 | . . . . . .
Mean 7.085 || 5.97 . . . . . . 654.7 1,928 . . . . . .
2.24b | 43.10 ! . . . . . . . . . . . . . 3,691 | . . . . . . . . . . . . .
2.248 I 43.10 | . . . . . . 29.38 3,694 | . . . . . . 2,412
2.24C 43.10 | . . . . . . 29.32 . . . . . . . . . . . . . 2,394
Mean . 43.10 | . . . . . . 29.35 | 3,693 | . . . . . . 2,403
2.192 || 14.335 | . . . . . . 9.97 | 1,294.5 | . . . . . . 812
2.19b 14.335 | . . . . . . 10.015 1,294.5 ! . . . . . . 818
Mean . 14.335 | . . . . . . 9.995] 1,294.5 . . . . . . 815
42 The Hydrolysis of Ammonium Acetate, Etc.
TABLE 20–Specific conductance at round temperatures of ammonium acetate
solutions containing ammonium hydroxide or acetic acid.

. | Milli-equivalents per liter. Specific conductance X 100.
Tem- || Experi- Salt
* * t e g s &l
tº Tº jº. *:::#;" |iº. ºf | *.
£o cx 10s |CA or ceX10°| L × 106 Lo X10* | L/Lo
218 2.16 || 11.94 || 11.88 Aj 5,057 3,809 | 1.328
2.7 | 12.015 12.075 B 5,010 || 3,833 || 1.307
2.17 | 11.90 23.61 AI 5,651 || 3,797 || 1.488
2.8 11.92 23.41 B 5,482 3,803 || 1.442
2.18 11.825 || 47.38 A 6,173 || 3,773 1.636
2.9 || 11.875 46.75 B| 6,093 3,789 | 1.608
2.12 || 6.08 || 5.985 A 2,606 || 1,963 | 1.328
2.4a || 6.00 6.25 B| 2,563
2.45 6.04 || 3:2; £ 2:... } | 1,944 | 1.818
2.13 6.10 | 12.055 A 2,944 1,969 | 1.495
2.5a 6.025 | 11.78 B 2,875
2.55 || 3 oil, ii.75 iſ 2.563) | 1,944 | 1.476
2.14 5.975 24.12 A 3,207 || 1,930 | 1.662
2.6 6.015 23.62 A. 3,150 1,942 | 1.622
306 2.26 28.76 31.91 Aj 3,430 2,355 | 1.457
3.1 || 27.53 || 88.6 . A 4,482 2,254 | 1.988
2.25 || 28.34 || 68.4 B 4,210 2,320 | 1.815
2.20al 9.96 || 10.025. A 1,146
3.300 g.g65 | 10.01. A 1:150 813 | 1.412
2.22 10.01 || 8.19 Bf 1,092 816 | 1.338
2.21 9.855 30.06 A 1,589 803 || 1.979
2.23 9.735 || 25.22 B 1,480 794 | 1.864
From the data given in table 90 the hydrolysis of the salt at 218° and
at 306° has been calculated in two different ways.
The first of these is that used by Noyes and Kato (section 73, Part VI)
in connection with their hydrolysis experiments at 156°. In this method,
the following expressions for hydrolysis equilibrium and for the empirical
relation of van’t Hoff between the ionization and concentration of salts
are combined:
L N* h(h+%
(# =–F
10°L
(#)---É.
L' T 1 h, 10°E.
* CAo
and thereby the values of ho and h, the hydrolysis of the salt at concen-
tration C in pure water and in the mixture respectively, are calculated.
Ao is the equivalent conductance of completely ionized ammonium acetate;
its values are 741 at 2.18° and 1020 at 306° (see section 10).
Section I2.-Hydrolysis of Ammonium Acetate. 43
In the second method the ion-concentration is, as before, calculated by
dividing the specific conductance of the solution (multiplied by 10°) by
the equivalent conductance of the completely ionized salt; and then the
concentration of the un-ionized salt is estimated under the assumption
that it has the same value as in a solution of an ordinary unhydrolyzed
salt of the same ionic type at the same ionic concentration. Then merely
by subtracting the un-ionized fraction (u) and the ionized fraction (y)
from unity, the hydrolyzed fraction (h) is obtained; that is, h = 1 — y — u.
In this calculation the mean ionization of potassium and sodium chlorides
as determined by Noyes and Coolidge (table 12, Part II) was used as a
basis. This calculation can give accurate hydrolysis values only when
the hydrolyzed fraction is large and the un-ionized fraction very small;
but under such conditions, which are in fact realized in the foregoing
experiments fairly well at 218° and in much higher degree at 306°, it is
the most direct method and a fairly reliable one. For example, suppose
the hydrolyzed, ionized, and un-ionized parts were 80 per cent, 18 per
cent, and 2 per cent respectively; then an error of even 3 per cent in
the ionized, and of 25 per cent in the estimated un-ionized fraction, would
make, if they lay in the same direction, an error of only one per cent
in the hydrolyzed fraction.*
Table 21 contains the results of the calculations. In the fifth and
sixth columns are given the values of the percentage hydrolysis (100h)
calculated by the first and second methods, respectively. In the seventh
column is given a mean derived from these. Since the results by the
second method are more accurate the greater the hydrolysis, in deriving
this mean a weight has been assigned to them equal to the percentage
hydrolysis, the results by the first method being always given a weight
of 100. It is desirable to combine the results by the two methods in some
such way as this, since any error in the conductance ratio L/Lo influences
them in opposite directions. In the last three columns of the table are
given the values of the percentage hydrolysis (100 ho) of the salt in
pure water at the same concentration C. The values in the first of these
columns are derived by the first method simultaneously with those of
100 h. Those in the second of these columns are calculated from the
mean value of 100h given in the seventh column by the equation
ha” — h(h+ CB/C) .
0 - (L/Lo)*
by the second method from the conductance in pure water.
Those in the last column are obtained directly
*The calculations were also made by still a third method, namely, that described
by C. W. Kanolt in Section 103, Part IX, but in this case where the hydrolysis is
very large the results were found to be much more influenced by the experimental
i. than those calculated by the first method. They are therefore not recorded
ere.
44 The Hydrolysis of Ammonium Acetate, Etc.
TABLE 21–Hydrolysis and ionization of ammonium acetate at 2.18° and 306°.
Salt in mixture. Salt in pure water.
rºs. consenu-i is *śjºioni. Percentage hydrolysis
ature. of salt C C Ioniza- g Ioniza- O
to C X 108 A or 'B' tion By By <> tion By From By
C C 100 y first l second Weight- 100 Yo first . second
method. I method. ed mean. method . * method,
218 11.91 0 e e º G tº e º e º ſo I & e º O & ſº I Gº G & © tº E 43.1 tº e º C Q tº e º O ſº º Gº 53.3
11.94 0.995 A 57.2 ſ 35.5 37.4 || 36.0 || 43.1 52.1 52.6 |. . . . . .
11.90 1.984. A 64.1 26.2 29.5 27.0 || 43.1 51.6 52.4 |......
11. 825 4.007 A '0.5 | 16.5 22.3 || 17.6 || 43.1 | 50.7 || 51.7 . . . . . .
Mean Q Q • * * * * * tº º ºs e º e tº Q tº º tº e e g is a • * * * *_G e o O Q & © 51.5 52.2 s • * * ~ *
12.015 1.005 B| 56.3 ſ 29.6 || 38.4 || 32.0 || 43.1 || 47.5 || 49.8 |. . . . . .
11.92 1.964 B) 62.1 | 21.5 || 31.8 24.0 || 43.1 || 47.4 | 50.5 ! . . . . . .
11. 875 3.937 B| 69.2 | 15.5 || 23.7 || 17.1 || 43.1 || 49.5 || 52.1 ! . . . .
Mean U → & © º O ſº gº tº e tº e I e º te e º 'º tº e º O ſº gº tº ºp © gº tº tº 48.1 50.8 © tº tº º º *
5.97 0 © E tº C G G | G. G. G. Q Q - e º ſº º gº º g º g º C g 43.6 Q Q & C ºs º º ºs e º ſº º 63.7
6.08 0,984 Al 57.8 || 36.0 | 38.0 || 36.5 || 43.6 || 52.4 || 52.9 . . . . . .
6.10 1.976 Al 65.1 | 27.1 30.0 27.8 || 43.6 ſ 52.2 52.9 |. . . . . .
5.975 4.037 Al 72.4 17.6 22.0 | 18.4 || 43.6 || 51.8 || 53.0 l. . . . . .
Mean º G | g º ºn G → ~ || C & G G & º tº tº o c e ºl tº dº º º ſº © e © tº e g º C tº 5.2.1 52.9 <e º º ge
6.02 1.038 B 57.5 30.6 || 38.4 || 32.7 || 43.6 || 48.6 50.7 | . . . . . .
6.02 1.957 Bf 64.3 || 25.2 || 30.9 || 26.5 43.6 50.6 52.0 | . . . . . .
6.015 3.927 B| 70.7 | 16.1 || 23.8 || 17.6 || 43.6 || 50.0 || 52.4 . . . . . .
Mean . . . . . . . . & G → tº º gº tº ſº e i º e º ºp gº tº © Q & Q & © ſº © Q @ Q tº 49.7 51.7 to G - © ſº
306 29.35 0 tº ſo © C C, Q & Q tº C & G G ºn tº º e º e º º 8.03 Q tº º Gº tº e º ſº tº e G 90.9
28.76 1.110 Al 11.69| 93.4 || 86.3 90.1 8.03| 94.8 || 92.4 . . . . . .
27.53 3.218. A 15.96 81.2 | 81.0 81.1 8.03| 91.0 | 90.9 Q Q &
Mean tº gº © e º 'o - e i º e º C G & © Cº © e º e g tº º e ºs tº º ºs º ºs e e 92.9 91.6 * Q ſº &
28.34 2.414 B] 14.56 85.0 | 82.8 | 84.0 8.03, 91.8 ſ 91.1 ! . . . . . .
10.00 tº ºn e º 'º © Q & © 2 e º e g º & g º º te e ſº 7.99 Q tº e C C D º º ºs tº e is 91.2
9.965 1.006 Al 11.29ſ 90.2 | 87.5 | 88.9 7.99 92.9 || 91.9 | . . . . . .
9.855 3.050 Al 15.81| 86.0 | 82.3 | 84.3 7.99 92.7 | 91.6 | . . . . . .
Mean . . & Cº - † º & © e º & © tº º O ſº º G - tº C & G T G & & ſº º º tº G tº gº 92.8 91.7 tº G & º e -
10.01 0.818 B 10.70 86.7 || 88.2 | 87.4 7.99 90.3 | 90.9 |. . . . . .
9.735 2. 591 B| 14.91| 85.8 || 83.4 | 84.7 7.99 92.3 || 91.5 ! . . . . . .
Mean: . . © a ſº º ſº tº o tº C & º G o > ſº C C & © to G © tº © . . ) tº º ſº tº tº 91.3 91.2 © C e C C

A comparison of the values of the percentage-hydrolysis (100 h) of
the salt in the mixture calculated by the two methods shows at 218° a
considerable divergence, especially in the experiments where an excess
of base was added. This was doubtless due largely to the destruction of
some of the base during the heating. At 306° where this was determined
and allowed for, and where the calculation by the second method is more
accurate, the agreement is far more satisfactory (except in the first
experiment which appears to be affected by some accidental error).
From an examination of the values of the percentage hydrolysis (100 ho)
of the salt in pure water it is seen that the experiments in which different
quantities of acid were added gave very concordant results, whether
Section 12.-Ionization of Water. 45
calculated directly by the first method or from the weighted mean value
of the percentage hydrolysis (100 h) for the salt in the mixture. The
mean value calculated from the latter is, however, to be considered the
most accurate. It will be seen that this agrees well in all cases with the
value given in the last column, which was calculated directly by the
second method from the conductance of the salt in pure water. To get
the best final value from each group of experiments we have combined
these two by assigning to the former a weight of 100 and to the latter
a weight equal to the percentage hydrolysis. Table 22 contains the
final hydrolysis values so obtained, the ionization values for the salt, the
ionization-constant of water calculated from them by the equation
Kw = KAKBho”/yo”, and the square root of the constant, which represents
the concentration CH of the hydrogen (or hydroxide) ion in pure water.
TABLE 22.—Ionization of water at 2.18° and 306.

Final results with ammonium acetate. * > x > Equivalents
Ionization
T age g of hyd º
it: | tº ºr "ºlº,";
liter. tion. ysis. Iters
go C 100 yo 100ho Kw X 1014 CH X 107
218 0.012 43.1 52.6 461 21.5
0.006 43.6 53.2 461 21.5
Mean 461 21.5
306 0.030 8.03 91.3 167 12.9
0.010 7.99 91.5 170 13.0
Mean 168 13.0
A comparison of these values of the ionization-constant with those
presented in Part VI by Noyes and Kato (48 at 100° and 223 at 156°)
shows that the constant is considerably greater at 218" than at the lower
temperatures, but that it has become much less at 306°. From a plot
of the values it appears probable that the maximum lies between 250°
and 275°.
46 The Hydrolysis of Ammonium Acetate, Etc.
13. SUMMARY.
In this article have been presented the results of conductivity measure-
ments with ammonium hydroxide, acetic acid, and ammonium chloride
at 18°, 218°, and 306°, and with sodium acetate at 306°. The final values
of the equivalent conductance will be found in table 14, and of the corres-
ponding ionization in table 17.
The equivalent conductance of completely ionized ammonium chloride,
which at 18° is nearly equal to that of potassium chloride, becomes 2 per
cent greater at 218° and 5 per cent greater at 306”; and that of sodium
acetate, which at 18° is only 71 per cent of that of sodium chloride,
becomes 86 per cent of it at 218° and 306°. The ionization of the two
salts is at all temperatures only a little less than that of sodium and potas-
sium chlorides; thus at 306° the differences are about 2 per cent and 4
per cent, respectively. The hydrolysis of these salts was not measured,
but was reduced substantially to zero by the addition of an excess of
the weak base or acid. Its value can, however, be calculated from the
ionization-constants of water, ammonium hydroxide, and acetic acid deter-
mined in this research”; and it is of interest to note that in 0.01 normal
solution both salts at 218° are 1.56 per cent hydrolyzed, and that at 306°
ammonium chloride is 4.1 and sodium acetate 3.4 per cent hydrolyzed,
while at 18° the hydrolysis is only 0.02 per cent.
The ionization of the slightly ionized substances, acetic acid and ammo-
nium hydroxide, decreases with great rapidity as the higher temperatures
are reached; thus the ionization-constants (X 10°), as determined from
the measurements at 218° and 306° presented in this article and from the
earlier ones at 18°, 100°, 156”, and 2.18° by Noyes and Cooper, and Noyes
and Kato, are as follows:
Acetic Acid. Ammonitfm Hydroxide.
18° 18, 3 17.2
100° 11.1 13.5
156° 5. 42' 6.28
218° 1.72 1.80
306° 0.139 0.093
*These calculations were made, for sodium acetate for example, by the substan-
2.
tially exact mass-action relation #º- #, wherein C represents the concentra-
&= - A
tion of the salt, h the hydrolyzed frºm of it, y the ionized fraction of the quantity
of it unhydrolyzed (C–Ch), YE the ionized fraction of the total quantity of free
base (Ch.), KA the ionization-constant for the acid, and Kw that for water. For the
ionized fractions Y and Ye in the mixture may be taken the value for the pure salt
and that for the pure base, respectively, when present alone at the concentration C,
the principle being here applied that in a mixture of largely ionized substances the
ionization of each is the same as if it were present alone at a concentration equal to
the sum of the concentrations.
Section I.3.−Summary. 47
In this article have also been presented determinations of the degree
of hydrolysis of ammonium acetate at 218° and 306°. This has been
derived from measurements of the change in conductance produced when
to the solution of the neutral salt acetic acid or ammonium hydroxide is
added. In 0.01 normal solution the pure salt was found to be 53 per
cent hydrolyzed at 218° and 91 per cent at 306°, while it can be shown
by calculation to be only 0.35 per cent hydrolyzed at 18°; thus showing
the enormous effect of temperature in increasing the hydrolysis of salts.
From the hydrolysis and ionization of the ammonium acetate and from
the ionization-constants of the acid and base the ionization of water itself
at 218° and 306° has been calculated. The final results together with
those obtained at lower temperatures by the previous workers in this
laboratory, are as follows. The values show the equivalents of hydrogen-
ion or hydroxide-ion present in ten million liters of pure water.
100° 156° 218° 306°
6.9 14.9 21.5 13.0
The considerable increase between 100° and 2.18° and the decrease
between 218° and 306°, indicating a maximum between these temperatures,
will be noted.
§