Thermodynamic study of the system lithium-hydrogen utilizing a mass spectrometric knudsen effusion method

The thermodynamic properties of the system LiH were investigated by the mass spectrometric Knudsen effusion method in the “plateau region” between 700 and 873°K. The enthalpy of the reaction LiH(s. sat. with Li) = Li(l. sat. with LiH) + 12H2(g) was determined. The resulting equilibrium pressure for hydrogen in the “plateau region” defined by this temperature range is given by the equation: logp(torr=−(1·040±0·021)×104T+13·30±0·26. The average standard enthalpy, and free energy of formation of LiH are: ΔH0298−21·8±0·5kcal/mole ΔH0298−16·77±0·5kcal/mole.