Gaseous thorium phosphide ThP g

Gingerich [1968GIN], [1969GIN2] has made two mass-spectrometric determinations of the pressures of ThP(g) existing over Th-B-P alloys at four temperatures between 2702 and 2804 K and gave partial pressures of the species in the three equilibria  

Gingerich [1969GIN] further estimated molecular parameters for ThP(g) by established spectroscopic approximations. We have repeated these calculations, using these estimates, and used third-law calculations to derive average values of Af//° (ThP, g, 298.15 K) = (537 + 8), (551 + 8), and (547 + 6) kJ-mol from the three reactions, with S° (ThP, g, 298.15 K) = (276.6 + 10.0) J-K -mor. The auxiliary data forP(g) and P2(g) were taken from Table IV-1 and [1989COXAVAG]. This indicates a value of Af//° (ThP, g, 298.15 K) = (545 + 30) kJ-moP, where the increased uncertainty includes those in the experimentation and the estimates of the thermal functions for ThP(g). This value shows that ThP(g) is always a quite minor species in the vaporisation of ThP, and in view of this and the paucity of the experimental data, the above values are given for information only, as for ThN(g). 

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