Chemical equilibria in hydrolysis of germanium tetrachloride and arsenic trichloride

Article abstract of DOI:10.1023/A:1019743231095

The chemical equilibria in the hydrolysis of high-purity germanium tetrachloride and arsenic trichloride at low water concentrations were studied by IR spectroscopy. The equilibrium constant of AsCl₃ hydrolysis was shown to correlate with the a

Full text of DOI:10.1023/A:1019743231095

Inorganic Materials, Vol. 38, No. 8, 2002, pp. 847–853. Translated from Neorganicheskie Materialy, Vol. 38, No. 8, 2002, pp. 1007–1014.
Original Russian Text Copyright © 2002 by Efremov, Potolokov, Nikolashin, Fedorov.
Chemical Equilibria in Hydrolysis
of Germanium Tetrachloride and Arsenic Trichloride
V. A. Efremov*, V. N. Potolokov**, S. V. Nikolashin**, and V. A. Fedorov**
* Mendeleev University of Chemical Technology, Miusskaya pl. 9, Moscow, 125820 Russia
** Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
e-mail: pgfed@igic.ras.ru
Received March 21, 2002
Abstract—The chemical equilibria in the hydrolysis of high-purity germanium tetrachloride and arsenic
trichloride at low water concentrations were studied by IR spectroscopy. The equilibrium constant of AsCl3
hydrolysis was shown to correlate with the activity coefficient of AsCl3. The equilibrium constants and thermo-
dynamic characteristics of GeCl4 and AsCl3 hydrolysis in CCl4 were calculated for the temperature range 283–
333 K.
earlier [5], water is in a monomeric form in CCl4 at con-
INTRODUCTION
centrations from 10–4 to 2 × 10–2 mol/l, and the ν(OH)
bands of H2O (3705 cm–1) and Ge(OH)Cl3 (3603 cm–1)
are well resolved. Carbon tetrachloride has no absorp-
tion bands in the OH stretching region. This situation,
ideal from the viewpoint of experiment, allows one to
accurately determine the equilibrium constants of reac-
tion (1) in CCl4 by monitoring the intensity of the νas
Fine purification of germanium tetrachloride and
arsenic trichloride with the aim of removing oxygen-
containing impurities, including hydrolysis products, is
a challenging problem. The presence of dissolved water
in these chlorides has a significant effect on the stability
of chalcogen- and silicon-containing impurities and
may lead to their transformations in the course of the
purification process [1, 2].
band of water (3705 cm–1) during hydrolysis.
Earlier work [3, 4] showed that, at low concentra-
tions of dissolved water in GeCl4 (<0.01 mol/l) and
AsCl3 (<0.04 mol/l), these chlorides hydrolyze pre-
dominantly according to the schemes
The equilibrium of reaction (1) in CCl4 was studied
at 293 K with vigorous stirring, using a thermostated
reactor and a flow cell made of optical quartz glass,
with an absorbing layer thickness of 10 cm [6]. High-
purity GeCl4, containing <10–4 mol/l H2O, was added
to appropriate amounts of CCl4 and water. The IR trans-
mission spectrum of the solution was recorded at 293 K
from 3200 to 4000 cm–1 before and after the introduc-
tion of GeCl4 (Fig. 1). As a result of hydrolysis, the
GeCl4 + H2O
AsCl3 + H2O
Ge(OH)Cl3 + HCl,
As(OH)Cl2 + HCl.
(1)
(2)
The purpose of this work was to investigate chemi-
cal equilibria in these reaction systems.
intensity of the νas band of water (3705 cm–1) decreases,
and the OH stretching band of Ge(OH)Cl3 emerges at
3603 cm–1. The approach to equilibrium in reaction (1)
was followed by repeatedly recording the spectrum of
the solution. The equilibrium reactant and product con-
centrations in reaction (1) were calculated by the rela-
tions
CHEMICAL EQUILIBRIUM IN GERMANIUM
TETRACHLORIDE HYDROLYSIS
The chemical equilibrium in the interaction of water
(10–3 to 4 × 10–2 mol/l) with germanium tetrachloride
was studied using both high-purity GeCl4 and mixtures
of GeCl4 and CCl4 (10–3 to 8.74 mol/l GeCl4).
'
"
H2O
A
– A
H2O
----------------------------
Ceq
=
,
(3)
Ge(OH)Cl (HCl)
Carbon tetrachloride was used as a solvent because
it is nonreactive with H2O and GeCl4 and also because
the GeCl4–CCl4 system behaves ideally and, accord-
ingly, the CCl4 solvent has no effect on the ν(OH) fre-
quency of Ge(OH)Cl3 and the molar extinction coeffi-
cient in the maximum of this band in the spectra of pure
GeCl4 and its solutions in CCl4. Moreover, as shown
3
εν (H O)l
as
2
"
A
H2O
-------------------
Ceq
=
O
,
(4)
(5)
H
2
εν (H O)l
as
2
Ceq
= Ci
– Ceq
,
Ge(OH)Cl
3
GeCl
GeCl
4
4
0020-1685/02/3808-0847$27.00 © 2002 MAIK “Nauka/Interperiodica”

848
EFREMOV et al.
described in [5]; and l is the thickness of the absorbing
layer (cm).
The equilibrium of reaction (1) in high-purity ger-
manium tetrachloride was studied over a wide range of
water concentrations by measuring the intensities of the
δ(H2O) band at 1600 cm–1 and the ν(OH) band of
Ge(OH)Cl3 at 3603 cm–1. To this end, a certain amount
of tritiated water was dissolved, with vigorous stirring,
without vaporization, in GeCl4 in a thermostated reac-
tor equipped with a flow cell. Only under such condi-
tions could we determine the equilibrium amounts of
monomeric water and GeCl4 hydrolysis products
(Ge(OH)Cl3 and HCl). The completeness of water dis-
solution in GeCl4 was checked by repeatedly recording
the spectrum of the solution from 1100 to 4000 cm–1
and also by a radiotracer technique [7]. From the max-
imum absorbances on the δ(H2O) band at 1600 cm–1
80
40
0
1
2
2
1
4000
3800
3600
3400
Wavenumber, cm–1
and the ν(OH) band of Ge(OH)Cl3 at 3603 cm–1 in the
spectrum of the solution and the maximum values of εν
on these bands, evaluated as described in [7], we calcu-
lated the equilibrium reactant and product concentra-
tions and the equilibrium constant of reaction (1) in
high-purity germanium tetrachloride (Table 1).
Fig. 1. IR transmission spectra of (1) H O and (2) H O +
2
2
–3
GeCl solutions in CCl ; 2.44 × 10 mol/l H O, 1.6 ×
4
4
2
−1
10 mol/l GeCl , 10-cm absorbing layer.
4
We obtained the following results:
where Ceq
, Ceq , Ceq , and Ceq
are the
O
(1) At water concentrations from 10–3 to 10–2 mol/l,
the equilibrium constant of reaction (1) varies very lit-
tle, indicating that the assumption as to the mechanism
of GeCl4 hydrolysis at low water concentrations is cor-
rect. The same is evidenced by the fact that, at water
concentrations below 10–2 mol/l, the molar extinction
coefficients in the maximum of the ν(OH) band of
Ge(OH)Cl3 calculated from the data on hydrolysis in
CCl4 and high-purity GeCl4 (using the equilibrium con-
Ge(OH)Cl
HCl
GeCl
H
3
4
2
Ge(OH)Cl3, HCl, GeCl4, and H2O concentrations
(mol/l) in the equilibrium mixture; Ci is the GeCl4
GeCl
4
'
"
2
concentration in the starting mixture; AH O and AH O
2
are the maximum absorbances on the νas band of water
in the spectrum of the H2O + CCl4 mixture and in the
spectrum of the equilibrium H2O + GeCl4 + Ge(OH)Cl3 +
stant of reaction (1) in CCl4, KC = 1.74 × 10–3) coincide
(Table 1).
(2) Increasing the water concentration to above
10−2 mol/l increases the equilibrium constant of reac-
tion (1), pointing to further replacement of chlorine
according to the scheme
HCl + CCl4 mixture, respectively; εν
is the molar
as(H2O)
extinction coefficient (l/(mol cm)) in the maximum of
the νas band of water (3705 cm–1) in the 293-K spec-
trum of the CCl4-containing solution, calculated as
GeCl4 + nH2O
Ge(OH)nCl4 – n + nHCl,
(6)
Table 1. Equilibrium constant of GeCl4 hydrolysis and mo-
lar extinction coefficient in the maximum of the ν(OH) band
of Ge(OH)Cl3 at 293 K
where n = 2 or 3. The same is evidenced by the appear-
ance of a broad absorption band in the range 3000–
3600 cm–1.
(3) The equilibrium constant of reaction (1) is inde-
pendent of the germanium tetrachloride concentration
in solution up to extrapure GeCl4, in full accordance
with the ideality of the GeCl4–CCl4 system.
CH O × 103, CGeCl × 102,
KC × 103 εν , l/(mol cm)
2
4
mol/l
mol/l
4.24
3.32
4.07
8.83
1.71
1.77
1.75
1.64
75.3
74.7
75.1
74.6
2.44
16.04
874.3*
CHEMICAL EQUILIBRIUM
IN ARSENIC TRICHLORIDE HYDROLYSIS
1.4–10
The equilibrium of reaction (2) was studied at water
concentrations from 10–3 to 6 × 10–2 mol/l, using the
same procedure as in the case of germanium tetrachlo-
* GeCl concentration of 8.743 mol/l corresponds to pure germa-
4
nium tetrachloride.
INORGANIC MATERIALS Vol. 38 No. 8 2002

CHEMICAL EQUILIBRIA IN HYDROLYSIS
849
ride. The equilibrium reactant and product concentra-
tions in reaction (2) were evaluated from the intensity
of the δ(H2O) band (1600 cm–1) in the spectrum of the
solution, using the maximum εν on this band deter-
mined as described in [7]. The results thus obtained are
summarized in Table 2.
80
40
0
1
2
2
It can be seen from Table 2 that, at water concentra-
tions in AsCl3 below 3 × 10–2 mol/l, the equilibrium
constant of hydrolysis varies little. This lends support
to the assumption that, at low water concentrations,
only the first stage of hydrolysis occurs. Raising the
water concentration to above 3 × 10–2 mol/l increases
the equilibrium constant of reaction (2), pointing to fur-
ther replacement of chlorine according to the scheme
1
AsCl3 + nH2O
As(OH)nCl3 – n + nHCl,
(7)
4000
3800
3600
3400
Wavenumber, cm–1
where n = 2 or 3.
Fig. 2. IR transmission spectra of (1) H O and (2) H O +AsCl
3
2
2
The effect ofAsCl3 concentration on the equilibrium
constant of reaction (2) was studied using CCl4 by the
same procedure as in the H2O–GeCl4–CCl4 system.
–3
–2
solutions in CCl ; 2.6 × 10 mol/l H O, 5.5 × 10 mol/l
4
2
AsCl , 10-cm absorbing layer.
3
A certain amount of high-purity AsCl3, containing
<10–4 mol/l H2O, was added to appropriate amounts of
CCl4 and water in a thermostated reactor. The IR trans-
mission spectrum of the solution was recorded at 293 K
from 3200 to 4000 cm–1 before and after the introduc-
tion of arsenic trichloride (Fig. 2). As a result of hydrol-
ysis, the intensity of the νas band of water (3705 cm–1)
decreased, and the ν(OH) band of As(OH)Cl2 emerged
ies little up to Ӎ10–2 mol/l AsCl3 and decreases at
higher AsCl3 concentrations, from 4.2 × 10–3 at low
concentrations to 1.8 × 10–4 in pure arsenic trichloride.
CONCENTRATION DEPENDENCES
OF THE EQUILIBRIUM CONSTANTS
OF GeCl4 AND AsCl3 HYDROLYSIS IN CCl4
at 3562 cm–1.
In the spectra of CCl4-containing solutions, the fre-
Our results show that, at low water concentrations in
the H2O–GeCl4–CCl4 system, the equilibrium constant
quency of the ν(OH) band of As(OH)Cl2 is substan-
tially higher than the 3525 cm–1 in the spectrum of
high-purity AsCl3, pointing to a weaker interaction of
the OH group of As(OH)Cl2 with CCl4 molecules.
Indeed, the energy of this interaction in the CCl4-con-
taining solution, evaluated by the Sokolov equation [8],
is 2.76 kJ/mol, against 5.44 kJ/mol in high-purity
AsCl3. Moreover, at AsCl3 concentrations above
0.1 mol/l, the νas band of water is notably shifted to
lower frequencies owing to the increased polarity of the
medium.
Table 2. Equilibrium constant of AsCl3 hydrolysis at 293 K
CH O × 103, mol/l
KC × 104
2
3.20
7.32
1.75
1.64
1.81
1.72
2.05
3.68
3.92
4.25
The decrease in νas frequency is accompanied by an
11.5
KC = 1.8 × 10–4
increase in the molar extinction coefficient εν of
as
water. In view of this, at the equilibrium reactant and
product concentrations in reaction (2), we refined the
15.6
25.7
35.9
46.4
56.6
εν of water using the experimentally determined
as
dependence of εν on the νas frequency in the spectrum
as
of the solution [7].
The equilibrium constants of arsenic trichloride
hydrolysis in CCl4 at low water concentrations are listed
in Table 3. The equilibrium constant of reaction (2) var-
INORGANIC MATERIALS Vol. 38 No. 8 2002

850
EFREMOV et al.
CCl4 using simple equilibrium distillation [10]. The
variation in vapor composition was followed by a
radiotracer (71Ge and 76As) technique [11].
–
logK
2
0.3
As shown earlier [10], equilibrium distillation of a
dilute solution can be described by the equation
0.2
0.1
0
1
logK = (m – 1)logϕ + logm.
(8)
–0.4
–0.8
–1.2
logϕ
–
Here, m = α for volatile impurities and m = 1/α for non-
volatile impurities, α is the separation coefficient, ϕ =
Gi/G0 is the degree of distillation (where Gi is the
amount of the solution in the still during distillation,
–0.1
–0.2
–0.3
–0.4
and G0 is the initial amount of the solution), and K =
yi/x0 is the distribution ratio (where yi is the impurity
content of the vapor phase during distillation, and x0 is
the initial impurity content of the solution). Since the
volatility of GeCl4 and AsCl3 is low compared to CCl4,
we take m = 1/α in Eq. (8).
Fig. 3. Log–log plots of the distribution ratio vs. degree of
distillation for dilute (1) germanium tetrachloride and
(2) arsenic trichloride solutions in carbon tetrachloride.
The experimental data on equilibrium distillation
are presented in Fig. 3.
of reaction (1) remains constant over a wide range of
GeCl4 concentrations.
The linear relationship between logK and logϕ
indicates that, in dilute GeCl4 and AsCl3 solutions in
CCl4, Henry’s law (α = const) is obeyed, and the solute
is present in only one chemical form.
At the same time, in the H2O–AsCl3–CCl4 system
the equilibrium constant of reaction (2) depends
strongly on AsCl3 concentration.
Using the results on equilibrium distillation and
It seems likely that this difference can be understood
in terms of the intermolecular interactions in the
GeCl4–CCl4 and AsCl3–CCl4 systems.
Eq. (8), we calculated the separation coefficients (αexp
and activity coefficients of solutes (γs) at low GeCl4 and
AsCl3 concentrations (Table 4).
)
As is well known, intermolecular interactions can be
characterized by the activity coefficient γ. In this con-
text, it is of interest to correlate the activity coefficients
of GeCl4 and AsCl3 in the binary systems in question
with the equilibrium constant of hydrolysis.
It follows from the data in Table 4 that the GeCl4–
CCl4 system behaves ideally, while the AsCl3–CCl4
system exhibits a significant positive deviation from
ideality. At low AsCl3 concentrations, the value of
γAsCl agrees well with the data on the liquid–vapor
3
equilibrium in the AsCl3–CCl4 system at high concen-
trations [12]. According to earlier results [12], the
AsCl3–CCl4 system can be classed with regular solu-
tions and described by the Van Laar equation with two
One way of determining the activity coefficient of a
component of the liquid phase is by investigating the
liquid–vapor equilibrium [9]. We studied the liquid–
vapor equilibria for dilute GeCl4 and AsCl3 solutions in
Table 3. Equilibrium constant of AsCl3 hydrolysis at 293 K as a function of AsCl3 concentration in CCl4
CAsCl × 103, mol/l
5.5
7.7
11
22
55
442
1410
4180
11930*
0.18
3
KC × 103
4.32
4.10
4.13
3.50
3.12
2.63
1.62
0.75
* Concentration of 11.93 mol/l corresponds to pure arsenic trichloride.
INORGANIC MATERIALS Vol. 38 No. 8 2002

CHEMICAL EQUILIBRIA IN HYDROLYSIS
851
virial coefficients A and B [8],
logγAsCl
logKC
3
0.25
0.20
A
1
2
---------------------------------------
logγ1 =
,
(9)
2
Ax1
–2.0
–2.5
–3.0
–3.5
1 + ----------------------
B(1 – x1)
0.15
0.10
0.05
0
B
---------------------------------------
logγ2 =
,
(10)
2
B(1 – x1)
1 + ----------------------
Ax1
where A = logγ1 for x1
1 − x1 0.
0, and B = logγ2 for
In the AsCl3–CCl4 system, A = B.
Therefore, we have A = B = logγAsCl (x
0) =
3
–2
–1
0
1
log1.85 = 0.267. The variation of γAsCl with AsCl3
3
logCAsCl
3
concentration at x < 0.1 can be calculated by the
formula
Fig. 4. Log–log plots of the (1) activity coefficient and
(2) equilibrium constant of reaction (2) vs. AsCl concen-
3
tration in CCl .
4
logγ
(x
0)
2
AsCl3
0.267
-------------------------------------
logγAsCl = -------------------------------------------- =
.
3
2
x
x
AsCl3
AsCl3
logKC
1 + --------------------
--------------------
1 +
1 – xAsCl
1 – xAsCl
3
3
(11)
–2.5
Figure 4 shows the concentration dependences of KC
–3.0
–3.5
and γAsCl . Because of the low water concentration, the
3
impurities present in the water have no significant
effect on γAsCl or γCCl . It can be seen that logKC and
3
4
logCAsCl vary with logCAsCl in a similar way.
3
3
Accordingly, logKC is a linear function of logγAsCl
3
0.1
0.2
logγAsCl
3
(Fig. 5) and can be represented in the form
Fig. 5. Log–log plot of the equilibrium constant of AsCl
3
logKC = logKC
+ 5.2logγAsCl .
3
(12)
(13)
hydrolysis vs. AsCl activity coefficient.
3
(AsCl
)
3
In the GeCl4–CCl4–H2O system, γGeCl = 1 and
10–1 mol/l GeCl4, and (2–9) × 10–3 AsCl3. The spectra
of the solutions were recorded continuously between
3200 and 4000 cm–1 until fully reproducible results
were obtained, indicating that the equilibrium of reac-
tions (1) and (2) was reached.
4
logKC = logKC
.
GeCl
4
Thus, the concentration effect on the equilibrium
constant of the reaction AsCl3 + H2O As(OH)Cl2 +
HCl in CCl4 is associated with the dependence of the
Table 4. Separation coefficients and activity coefficients for
dilute GeCl4 and AsCl3 solutions in CCl4 (pressure, 105 Pa;
boiling point, 76.5°C; equilibrium solute concentrations
from 10–3 to 10–4 wt %)
activity coefficient γAsCl in the AsCl3–CCl4 system on
3
the AsCl3 concentration.
EQUILIBRIA
Boiling
Solute
αideal
αexp
γs
IN GERMANIUM TETRACHLORIDE
AND ARSENIC TRICHLORIDE HYDROLYSIS
AT DIFFERENT TEMPERATURES
point, °C
GeCl4
AsCl3
83.1
1.20
5.60
1.20
3.03
1.00
1.85
The effect of temperature on the equilibrium of
reactions (1) and (2) in CCl4 was studied using solu-
tions containing (2–6) × 10–3 mol/l H2O, 3 × 10–3 to 5 ×
130.1
INORGANIC MATERIALS Vol. 38 No. 8 2002

852
EFREMOV et al.
1
2
1
2
3
3
4000
3800
3600
3400
Wavenumber, cm–1
4000
3800
3600
3400
Wavenumber, cm–1
Fig. 6. IR transmission spectra of an H O + GeCl solution
Fig. 7. IR transmission spectra of an H O + AsCl solution
2 3
2
4
in CCl at (1) 283, (2) 303, and (3) 333 K; 10-cm absorbing
in CCl at (1) 283, (2) 303, and (3) 333 K; 10-cm absorbing
4
4
layer.
layer.
with increasing temperature, ∆G0 decreases and ∆S0
increases. These results demonstrate that reactions (1)
and (2) are endothermic.
Figures 6 and 7 show the spectra of H2O + GeCl4
and H2O + AsCl3 solutions in CCl4 at different tem-
peratures. With increasing temperature, the intensity
of the νas band of water (3705 cm–1) decreases, while
the intensities of the ν(OH) bands of Ge(OH)Cl3
(3603 cm–1) and As(OH)Cl2 (3562 cm–1) decrease.
These results indicate that raising the temperature
drives reactions (1) and (2) to the right. From the
maximum absorbance on the νas band of water in
the spectra of the solutions studied and the maxi-
mum molar extinction coefficient on this band, we
evaluated, by Eq. (3), the equilibrium reactant and
product concentrations and the equilibrium con-
stants of reactions (1) and (2) at different tempera-
tures (Table 5).
Using the mean standard heat effects of reactions (1)
and (2) and the standard heats of formation of the com-
pounds involved [13], we estimated the standard heats of
logKC
–2.0
–2.2
The equilibrium constants of reactions (1) and (2)
show Arrhenius behavior (Fig. 8), with best fit equations
–2.4
2
logKC = 1.039 – 1113/T,
logKC = 0.928 – 974/T.
(14)
(15)
–2.6
–2.8
1
The temperature-dependent equilibrium constants
of reactions (1) and (2) were used to evaluate the mean
standard heat effect of reaction ∆H0, standard Gibbs
energy change ∆G0, and standard entropy change ∆S0
(Table 5). In the temperature range studied, the ∆H0 val-
ues of reactions (1) and (2) vary little. At the same time,
3.0
3.2
3.4
103/T, K–1
3.6
Fig. 8. Arrhenius plots of K for reactions (1) and (2).
C
INORGANIC MATERIALS Vol. 38 No. 8 2002

CHEMICAL EQUILIBRIA IN HYDROLYSIS
853
REFERENCES
Table 5. Equilibrium constants and thermodynamic charac-
teristics of GeCl4 and AsCl3 hydrolysis in CCl4
1. Fedorov, V.A., High-Purity Substances and Materials for
Microelectronic and Optical Applications, in Teoreti-
cheskaya i prikladnaya neorganicheskaya khimiya (The-
oretical and Applied Inorganic Chemistry), Moscow:
Nauka, 1999, p. 400.
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aration of Extrapure Arsenic from Lewisite Detoxication
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∆H0,
kJ/mol
∆G0,
kJ/mol
∆S0,
kJ/(mol K)
T, K KC × 10–3
GeCl4 + H2O = Ge(OH)Cl3 + HCl
283.15
293.15
298.15
303.15
313.15
323.15
333.15
1.30
1.77
2.05
2.36
3.09
3.97
5.04
20.75
20.75
20.75
20.75
20.75
20.75
20.75
15.64
15.45
15.34
15.25
15.05
14.86
14.65
18.05
18.08
18.14
18.16
18.20
18.23
18.37
AsCl3 + H2O = As(OH)Cl3 + HCl
283.15
293.15
298.15
303.15
313.15
323.15
328.15
3.06
4.02
4.57
5.18
6.57
8.22
9.15
18.32
18.32
18.32
18.32
18.32
18.32
18.32
18.32
13.63
13.44
13.35
13.26
13.08
12.90
12.81
12.70
16.56
16.65
16.67
16.69
16.73
16.77
16.79
16.84
7. Efremov, V.A., Efremova, T.A., Efremov, A.A., and
Kharitonov, Yu.Ya., IR Spectroscopic Determination of
Water and Hydrolysis Products in GeCl4, SnCl4, and
AsCl3, Vysokochist. Veshchestva, 1991, no. 5, pp. 215–220.
333.15 10.15
8. Sokolov, N.D., Hydrogen Bond, Usp. Fiz. Nauk, 1955,
formation of Ge(OH)Cl3 and As(OH)Cl2 in CCl4-contain-
ing solutions: ∆fH0(298 ä, Ge(OH)Cl3) = –663.9 kJ/mol
and ∆fH0(298 ä, As(OH)Cl2) = –402.8 kJ/mol.
vol. 57, no. 2, pp. 205–278.
9. Kogan, V.G., Geterogennye ravnovesiya (Heterogeneous
Equilibria), Leningrad: Khimiya, 1968.
10. Efremov, A.A. and Zel’venskii, Ya.D., Chemical Forms
of Sulfur and Arsenic Trace Impurities in Trichlorosi-
lane, Materialy vsesoyuznogo soveshchaniya po metodam
polucheniya osobo chistykh veshchestv (Proc. All-Union
Conf. on the Techniques for Preparing High-Purity Sub-
stances), Moscow: NIITEKhIM, 1967, pp. 55–66.
11. Zel’venskii, Ya.D., Efremov, A.A., and Shalygin, V.A.,
Application of Radioisotopes in the Investigation and
Development of Techniques for Preparation of Pure and
Extrapure Substances, in Metod izotopnykh indikatorov
v nauchnykh issledovaniyakh i v promyshlennom proiz-
vodstve (Scientific and Technological Applications of
the Radiotracer Technique), Moscow: Atomizdat, 1971,
pp. 311–317.
12. Efremov, A.A., Fedorov, V.A., Filippov, E.P., and Efre-
mov, E.A., Liquid–Vapor Equilibria in AsCl3–Chloroal-
kane Binary Systems, Elektron. Tekh., Ser. 6: Mater.,
1973, no. 4, pp. 43–48.
13. Termicheskie konstanty veshchestv (Thermal Constants
of Substances), Glushko, V.P., Ed., Moscow:Akad. Nauk
SSSR, 1965, issue 1, pp. 24, 48; 1968, issue 3, p. 98;
1970, issue 4.4.1, p. 418.
CONCLUSION
The equilibria in GeCl4 and AsCl3 hydrolysis in
CCl4 were studied at low water concentrations. The
results demonstrate that the equilibrium constant of the
reaction GeCl4 + H2O
Ge(OH)Cl3 + HCl is indepen-
dent of the GeCl4 concentration in solution up to extra-
pure GeCl4, because the GeCl4–CCl4 system behaves
ideally (γGeCl = 1).
4
The equilibrium constant of the reaction AsCl3 +
H2O
tion in CCl4, which is associated with the variation in
γAsCl :logKC = logKC(AsCl ) + 5.2logγAsCl
As(OH)Cl2 depends on the AsCl3 concentra-
.
3
3
3
We calculated the equilibrium constants and ther-
modynamic characteristics of GeCl4 and AsCl3 hydrol-
ysis in CCl4 in the range 283–333 K and the standard
heats of formation of Ge(OH)Cl3 and As(OH)Cl2.
INORGANIC MATERIALS Vol. 38 No. 8 2002