Mass-spectrometric study of (indium + chlorine)(g) Enthalpies of formation of InCl(g), In 2Cl 2(g), In 2Cl 4(g), InCl 3(g), and In 2Cl 6(g)

Abstract

The gaseous phase in equilibrium with InCl(s or l), InCl 2(s or l), or InCl 3(s) was analysed by the Knudsen-cell mass-spectrometric method. InCl 3(g) and In 2Cl 6(g) are the main species vaporizing from InCl 3(s); InCl(g), In 2Cl 2(g), In 2Cl 4(g), and InCl 3(g) from InCl(s or l); and In 2Cl 4(g), InCl 3(g), InCl(g), In 2Cl 6(g), and In 2Cl 2(g) from InCl 2(s). The gas-phase analysis was performed by studying the ionization-efficiency curves and ionic-intensity ratios as a function of the temperature of vaporization and chemical composition in (indium + chlorine) for every In x Cl y + ion ( x = 1, 2 and y = 0 to 5). Enthalpies of formation were deduced from vaporization and gas-phase equilibria: Δ f H m o(InCl 3, g, 298.15 K) = −(375.7 ± 5.0) kJ · mol −1, Δ f H m o(In 2Cl 6, g, 298.15 K) = −(883.7 ± 10.0) kJ · mol −1, Δ f H m o(InCl, g, 298.15 K) = −(68.2 ± 4.6) kJ · mol −1, Δ f H m o(In 2Cl 4, g, 298.15 K) = −(573.2 ± 12.6) kJ · mol −1. A lower bound was calculated for InCl 2(g): Δ f H m o(InCl 2, g, 298.15 K) ⩾ −201 kJ · mol −1.