The heat capacity of natural lead molybdate (wulfenite, PbMoO4) has been measured by the method of vacuum adiabatic calorimetry over the temperature range of (55 to 320) K, and its thermodynamic functions have been calculated. The obtained standard values are as follows: Cpdeg (298.15) = (119.41 +- 0.13) J*mol-1*K-1, Sdeg (298.15) = (168.33 +- 2.06) J*mol-1*K-1, ?Hdeg = (23095 +- 50) J*mol-1. For extrapolation of heat capacity values to absolute zero, the equation C(T) = (AT-1/ass + 1)-1/a has been used, where parameter a is the power at which the heat capacity verges toward the Dulong and Petit limiting value, and parameter ss reflects structural anisotropy of the compound and can possess values from 1 to 3. The values of parameters found by means of linearization were a = 0.61 and ss = 1.9. An error for the extrapolation data to absolute zero has been estimated based on the results of heat capacity measurements of the isostructural compound calcium tungstate, CaWO4. The values of the wulfenite heat capacity over the range of (0 to 55) K have also been calculated by the semiempirical method MNDO with the help of a program package on quantum-chemical computation (MOPAC) and according to the method of interatomic potentials within the bounds of dynamics of crystal lattice theory using the computer program LADY.
Compounds
#
Formula
Name
1
MoO4Pb
lead(II) molybdenum(VI) oxide
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
1
Molar heat capacity at constant pressure, J/K/mol ; Crystal