ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2009, Vol. 54, No. 9, pp. 1474–1478. © Pleiades Publishing, Inc., 2009.
PHYSICOCHEMICAL ANALYSIS
OF INORGANIC SYSTEMS
Phase Equilibrium System of RbCl–PrCl –HCl(12.86 mass %)–
3
H O at 298.15 K and Standard Molar Enthalpy of Formation
2
1
of New Solid-Phase Compound
a
b
a
a
a
Zhanping Qiao , Junlin Gao , Lihong Zhuo , Meili Zhang , and Shuai Zhang
a
College of Chemistry and Pharmacy Engineering, Nanyang Normal University, Nanyang, Henan, 473061, China
b
Department of Architecture Engineering, Henan Polytechnic Institute, Nanyang, Henan, 473009, China
e-mail: nyqiaozp@yahoo.com.cn
Received December 27, 2007
Abstract—The equilibrium solubility of the quaternary system RbCl–PrCl –HCl–H O was determined at
3
2
2
98.15 K and the corresponding equilibrium diagram was constructed in this paper. The quaternary system is
complicated with three equilibrium solid phases, RbCl, RbPrCl · 4H O (1:1 type) and PrCl · 6H O, of which
4
2
3
2
the new compound RbPrCl · 4H O was found to be congruently soluble in the system. The new compound
4
2
obtained was identified and characterized by the methods of X-ray diffraction, thermogravimetry, and differen-
tial thermogravimetry. The compound loses its crystal water by one step at 343 K to 453 K. The standard molar
–
1
enthalpy of solution of RbPrCl · 4H O in deionized water was measured to be –24.53 ± 0.22 kJ mol by heat con-
4
2
–1
duction microcalorimetry. Its standard molar enthalpy of formation was calculated to be –2743.20 ±1.09 kJ mol .
DOI: 10.1134/S0036023609090228
1
Phase Equilibria of quaternary systems of CsCl– H O (R = Nd, Sm, Eu, Gd, Lu), their phase chemical
2
RCl –HCl (13%)–H O (R = La, Pr, Nd, Sm, Y, Ce, Eu, reaction have both similarities (all having 2:1 type com-
3
2
Gd, Tm, Lu), of MCl–RCl –HCl(13 %, 22%)–H O (M = pound) and dissimilarities (all having various types of
3
2
other compounds). Similarly, the quaternary systems
CsCl–RCl –HCl–H O (R = Y, Tm) also have both simi-
K, Rb; R = Ce, Gd), of CsCl–RCl –CH COOH (42%)–
3
3
H O (R = La, Pr, Sm) at 298.15 K have been reported
3
2
2
larities and dissimilarities. For the rare alkali metal and
rare-earth chloride systems CsCl–RCl –HCl–H O and
[1–12]. Twenty-one new compounds were obtained
from the systems, they are RbRCl · 4H O (R = Ce, Gd)
3
2
4
2
CsCl–RCl –CH COOH (42%)–H O (R = La, Pr, Nd,
and CsRCl · nH O (R = La Ce, Pr, Nd), Cs RCl · nH O
3
3
2
4
2
2
5
2
Sm), effect of hydrochloric acid and acetic acid in both
systems is the same.
(
R = Sm, Nd, Eu, Gd, Lu), Cs RCl · nH O (R = La, Ce,
3 6 2
Pr), Cs R Cl · nH O (R = Tm, Y), Cs RCl · nH O (R =
3
2
9
2
4
7
2
In order to contrast the difference of the phase
chemical relationship of the rare alkali metal and rare-
earth chloride in aqueous salt systems and find more
Gd, Y, Lu), Cs EuCl · 14H O and Cs Lu Cl · 29H O.
5
8
2
9
5
24
2
Optical investigation shows that some of them have
upconversion fluorescence properties in the near infra-
red region. Comparison of the quaternary systems finds
that the quaternary system KCl–RCl –HCl–H O is sim-
phase equilibrium information on the RbCl–RCl –HCl–
3
H O quaternary systems, it is necessary for us to further
2
3
2
study the phase equilibria systematically. The present
paper is concerned with the solubility and phase equi-
librium relation of the RbCl–PrCl –HCl(12.86 %)–H O
ple. However, for the quaternary system RbCl–GdCl3–
HCl–H O is simple when the concentration of HCl is
2
3
2
below 22% and complicated when HCl is over 22%.
system at 298.15 K. In this system, new solid-phase
compound was found and related measurement of its
properties was also done.
For the quaternary system RbCl–CeCl –HCl–H O is
3
2
complicated when the concentration of HCl is 13%.
These indicate that their phase chemical reaction have
both similarities and dissimilarities. For the three qua-
ternary systems CsCl–RCl –HCl–H O (R = La, Ce, Pr),
3
2
EXPERIMENTAL SECTION
their phase chemical reactions are very similar because
they all have the 3:1 type and 1:1 type compounds.
Preparing Samples
All chemicals (RbCl) and solvents [H O and HCl
While for the five quaternary systems CsCl–RCl –HCl–
2
3
(
37 mass %)] were analytically pure and purchased
1
The article is published in the original.
from the market. PrCl · 6H O was prepared by the reac-
3 2
1
474