Heat Capacity and Enthalpy Measurements on Aluminum Carbide (AlC) From 15 to 1173 °K. Thermodynamic Properties From 0 to 2000 °K.

Measurements of the heat capacity and relative enthalpy were made on aluminum carbide (AlC) from 15 to 1173 °K. The thermodynamic properties were calculated up to 2000 °K from the data by judicious extrapolation above 1173 °K. In conjunction with the heat-of-formation data on AlC obtained by King and Armstrong and by Mah, second- and third-law analyses have been made of the thermodynamics of several high-temperature vapor-equilibrium reactions involving AlC.

Thermodynamic Properties of Magnesium Oxide and Beryllium Oxide from 298 to 1,200 °K.

As a step in developing new standards of high-temperature heat capacity and in determining accurate thermodynamic data for simple substances, the enthalpy (heat content) relative to 273 °K, of high purity fused magnesium oxide, MgO, and of sintered beryllium oxide, BeO, was measured up to 1,173 °K. A Bunsen ice calorimeter and the drop method were used. The two samples of BeO measured had surface-to-volume ratios differing by a factor of 15 or 20, yet agreed with each other closely enough to preclude appreciable error attributable to the considerable surface area.

Thermodynamic Properties of Thorium Dioxide From 298 to 1,200 °K.

As a step in developing new standards of heat capacity applicable up to very high temperatures, the heat content (enthalpy) of thorium dioxide, ThO, relative to 273 °K, was accurately measured at ten temperatures from 323 to 1,173 °K. A Bunsen ice calorimeter and a drop method were used to make the measurements on two samples of widely different bulk densities. The corresponding heat-capacity values for the higher density sample are represented within their uncertainty (estimated to be ±0.