Mass Spectrometric Determination of the Heats of Formation of the Silicon Subchlorides SiCl(g), SiCl2(g) and SiCl3(g)

Abstract

An effusion-mass spectrometric determination of the reaction of SiCl4(g) with Si(c, l) in the temperature range 1593–1792 K has been completed. Second and third law reaction enthalpies were obtained for SiCl4(g)+ Si(g)= 2SiCl2(g), SiCl4(g)+ SiCl2(g)= 2SiCl3(g), and SiCl2(g)+ Si(g)= 2SiCl(g). From the heats of reaction third law ΔHf298 values of 47.1 ± 0.6, –40.6 ± 0.6 and –93.3 ± 0.5 kcal mol–1 were obtained for SiCl(g), SiCl2(g) and SiCl3(g), respectively. For the dissociation of SiCl(g)→(3P0)Si(g)+(2P3/2)Cl(g) a third law dissociation energy value of 88.6 ± 0.6 kcal mol–1 was calculated.