Thermodynamics of acid dissociation of aqueous bisulfite ion: ΔH0, ΔCP0, and ΔV0 at 298.15 K

Abstract

Calorimetric measurements of the enthalpy of protonation of sulfite ion and the enthalpy of proton transfer from bisulfite ion to carbonate ion have led to two independent values for the standard enthalpy of the acid dissociation reaction represented by HSO3−(aq) = H+(aq) + SO32− (aq). Further calorimetric and density measurements have led to apparent and partial molar heat capacities and volumes for sulfite and bisulfite ions. Results of all of these measurements are summarized by ΔH0 = −3.59 ± 0.10 kJ mol−1, ΔCP0 = −262 ± 7 J K−1 mol−1, and ΔV0 = −28.7 ± 1.0cm3 mol−1 for the acid dissociation of HSO3− (aq) at 298.15 K. These results are used for thermodynamic calculations of the temperature and pressure dependence of the equilibrium constant for acid dissociation of HSO3− (aq).