THE FIRST IONIZATION CONSTANT OF HYDROGEN SULFIDE IN WATER

Recent developments in radioactive tracing techniques and the availability of radioactive tracers were exploited, together with standard conductance techniques to determine the thermodynamic first ionization constant of hydrogen sulfide: K/sub 1/ = STA(m/sub H+/) (m/sub HS-/)/(m/sub H2S/)! STA( g/ sub H+/) ( gamma /sub HS-/)/( gamma /sub H2S/)!. The apparent ionization constant of H/sub 2/S was determined at successively lower concentrations of H/ sub 2/S in the range of 1 x 10/sup -3/ to 16 x 10/sup -3/ molal, and a true thermodynamic constant evaluated by extrapolation to infinite dilution. Water with a conductivity of 0.25 x 10/sup -6/ mho at 25 deg was obtained by distilling deionized water under a hydrogen atmosphere directly into the reaction fiask and proceeding with the experiment as soon as the water reached thermal equilibrium with the thermostat. The values obtained for the first ionization constant were 0.271 x 10/sup -7/ plus or minus 4%, 0.87 x 10/sup -7/ plus or minus 4%, and 1.52 x 10/sup -7/ plus or minus 7% at 0, 25, and 50 deg , respectively. These values are in general agreement with values obtained by previous investigators, taking into account the high ionic strengths employed by them. (auth)