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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Dysprosium formate with Holmium formate and Water
Components:
(1) Dysprosium formate; Dy(CHO2)3; [3252-58-2]
NIST Chemistry WebBook
for detail
(2) Holmium formate; Ho(CHO2)3; [3252-59-3]
NIST Chemistry WebBook
for detail
(3) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
Original Measurements:
Plyushchev, V.E.; Shklover, P.P.; Shkolnikova, L.M.; Kuznetsova, C.P.; Nadezhdina, G.V., Dokl. Acad. Nauk SSSR 160, 366-9 (1965).
Variables:
Temperature = range of 25 ºC to 50 ºC
Prepared By:
Chr. Balarew and St. Trendafilova
Experimental Remarks:
Authors' Comment:
The solubility is expressed as % oxide because, at 50°C, hydrolysis possibly occurs. Analysis of crystal phases dried at room temperature shows a composition Me(CHO
2
)
3
·
n
H
2
O where
n
= 0-0.5 for the formates from La to Ho. However the presence of water could not be confirmed by IR spectroscopy. For Eu and Gd
n
= 0.
Experimental Data:
(Notes on the Nomenclature)
(Please see footnotes following the table(s).)
Part 1. Solubility polytherm of the Dy(CHO
2
)
3
-H
2
O system.
t/°C
Chemical
1
Phase
Mass Fraction w
1
m
1
[mol kg-1]
a
Chemical
2
Mass Fraction w
2
a
m
2
[mol kg-1]
a
Solid Phase(s)
b
25
Dy2O3
Liquid phase
4.83
0.136
Dy(CHO2)3
7.7
0.280
A
40
Dy2O3
Liquid phase
4.91
0.138
Dy(CHO2)3
7.82
0.285
A
50
Dy2O3
Liquid phase
4.43
0.124
Dy(CHO2)3
7.06
0.255
A
Part 2. Solubility polytherm of the Ho(CHO
2
)
3
-H
2
O system.
t/°C
Chemical
1
Phase
Mass Fraction w
1
m
1
[mol kg-1]
a
Chemical
2
Mass Fraction w
2
a
m
2
[mol kg-1]
a
Solid Phase(s)
b
25
Ho2O3
Liquid phase
10.39
0.307
Ho(CHO2)3
16.50
0.659
B
40
Ho2O3
Liquid phase
11.52
0.345
Ho(CHO2)3
18.29
0.746
B
50
Ho2O3
Liquid phase
8.20
0.236
Ho(CHO2)3
13.02
0.499
B
Notes:
a
These values were calculated by the compilers.
b
The solid phases are: A = Dy(CHO
2
)
3
; B = Ho(CHO
2
)
3
.
Method/Apparatus/Procedure:
The isothermal method was used. The mixtures were stirred for one week. Dy
3+
and Ho
3+
were determined complexometrically.
1
The solid phases were analyzed by DTA and IR spectroscopy.
Source and Purity of Materials:
The formate salts were prepared by reacting the respective hydroxide with formic acid. The Ho
2
O
3
and Dy
2
O
3
had 0.05-1.5 mass % and 2.3 mass % impurities, respectively. The formic acid has
n
D
20
= 1.3712.
Estimated Errors:
Temperature: The temperature was controlled to within ±0.1 °C.
References:
1
L. I. Martinenko, Nauchn. Dokl. Vyssh. Shk. Khim. Khim. Tekhnol.
N4
, 718 (1958).