Vaporization of Aluminum Phosphide

Abstract

The vaporization of aluminium phosphide was investigated over the temperature range of 1270°–1800°K using the Knudsen effusion method in combination with mass spectrometry. Aluminium phosphide decomposes according to the reaction $$2{\mathrm{AlP}}_{\mathrm{(s)}}\text{\hspace{0.17em}→\hspace{0.17em}2}{\mathrm{Al}}_{\mathrm{(g)}}\mathrm{\hspace{0.17em}+\hspace{0.17em}}{\mathrm{P}}_{\text{2(g)}}.$$ The enthalpy for Reaction (1), ${\mathrm{\Delta H°}}_{298}$ , as calculated by the second‐ and third‐law method is 261.7 ± 5.9 and 254.8 ± 2.1 kcal/mole, respectively. The second‐ and third‐law enthalpies ${\mathrm{\Delta H°}}_{298}$ for the reaction $$4{\mathrm{Al}}_{\mathrm{(g)}}\mathrm{\hspace{0.17em}+\hspace{0.17em}}{\mathrm{Al}}_2{\mathrm{O}}_{\text{3(s)}}\text{\hspace{0.17em}→\hspace{0.17em}3}{\mathrm{Al}}_2{\mathrm{O}}_{\mathrm{(g)}}$$ have been determined as − 10.7 ± 2.0 and − 10.5 ± 0.5 kcal/mole, respectively. The error terms given represent the standard deviation. On the basis of a selected value of 255.0 ± 6.0 kcal/mole for the enthalpy of Reaction (1) and of pertinent literature data, the standard heat of aluminium phosphide formation, ${\mathrm{\Delta H°}}_{\text{f,298}}\text{\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}28.2\hspace{0.17em}±\hspace{0.17em}3.2}\mathrm{kcal}/\mathrm{mole}$ is obtained.