The heat capacity of one Na-rich and two K-rich samples of the NaCl-KCl (halite-sylvite) crystalline solution was investigated between 5 and 300 K. It deviated positively from ideal behaviour with a maximum at 40 K.The thereby produced excess entropy at 298.15 K was described by a symmetric Margules mixing model yielding W Sm =8.73 J/mol/K. Using enthalpy of mixing data from the literature and our data on the entropy, the solvus was calculated for apressure of 10^5 Pa and compared with the directly determined solvus.The difference between them can be attributed to the effect of Na-K short range ordering (clustering).
Compounds
#
Formula
Name
1
ClNa
sodium chloride
2
ClK
potassium chloride
Datasets
The table above is generated from the ThermoML associated json file (link above).
POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied;
the numbers refer to the table of compounds on the left.
Type
Compound-#
Property
Variable
Constraint
Phase
Method
#Points
POMD
2
1
Molar heat capacity at constant pressure, J/K/mol ; Crystal