A SPECTROPHOTOMETRIC STUDY OF HYDROGEN SULPHIDE IONISATION IN AQUEOUS SOLUTIONS TO 350°C

Abstract

The ultraviolet spectra of dilute aqueous solutions have been measured up to 350°C. From these data, the molal equilibrium constant, K1, for the first ionisation of H2S has been calculated. Over the temperature range from 25 to 350°C at saturated vapour pressures, K1 varies from 6.99 (25°C) to 8.89 (350°C). Standard thermodynamic data for H2S (aq) and HS− are presented for the temperature range 25 to 300°C at 100 bar. The shift of the charge-transfer-to-solvent spectrum of HS− with increasing temperature is attributable to an expansion of hydrosulphide ion solvation environment.