Vaporization of Aluminum Arsenide

Vaporization of aluminum arsenide was studied, using the Knudsen effusion method. Aluminum arsenide decomposes according to the reaction $${\mathrm{AlAs}}_{(\mathrm{s})}\to {\mathrm{Al}}_{(\mathrm{g})}+\frac{1}{2}{\mathrm{As}}_{\text{2(}\mathrm{g})}.$$ For the reaction $${\mathrm{Al}}_{(\mathrm{s})}+{\mathrm{As}}_{(\mathrm{s})}\to {\mathrm{AlAs}}_{(\mathrm{s})},$$ ΔH₂₉₈ is found to be —35.4±3.1 kcal.