A fluorine bomb calorimetric determination of the standard molar enthalpy of formation of silicon disulfide SiS2(cr) at the temperature 298.15 K. Enthalpies of dissociation of Si–S bonds

✍ Scribed by Iwona Tomaszkiewicz; G.A. Hope; P.A.G. O'Hare

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 224 KB
• Volume: 29
• Category: Article
• ISSN: 0021-9614
• DOI: 10.1006/jcht.1997.0221

✦ Synopsis

A synthesis of high-purity silicon disulfide SiS2 is described, and the F.t.-Raman spectrum of the solid is reported for the first time. The standard massic energy of reaction of SiS2(cr) with fluorine was measured in a bomb calorimeter. The combustion reaction was shown to proceed as follows: SiS2(cr) + 8F2(g) = SiF4(g) + 2SF6(g). The derived standard molar enthalpy of formation is: DfH °m(SiS2, cr, 298.15 K) = -(254.6 2 2.9) kJ•mol -1 . This value differs significantly from those determined by solution-reaction calorimetry, but is in fair agreement with results obtained by means of third-law treatments of high-temperature equilibria. The ratio of molar enthalpies of dissociation of the ''first'' and ''second'' bonds in SiS2(g), k = D°m(S-SiS)/D°m(SiS) = (0.57 2 0.03), is similar to ks reported previously for SiO2 and SiSe2.