Thermodynamics of the sublimation of calcium molybdate

The sublimation of CaMoO_4(s) is studied by high-temperature mass spectrometry at 1530–1770 K. CaMoO_4(g) and MoO_3(g) molecules are found to be present in the vapor; their vapor pressure is determined. The pressure of the CaMoO_4(g) molecule vapor is determined to be logp = ? 19 685/T + 5.52. The heat of sublimation ΔH _{s, 0} ^o (CaMoO_4(s)) = 446 ± 40 kJ/mol has been determined using the third law of thermodynamics. The atomization energy of the CaMoO_4(g) molecules is calculated to be ΔH _{at, 0} ^o (CaMoO_4(g)) = 2910 ± 40 kJ/mol.