Equilibrium partial pressures of strong acids over concentrated saline solutions—II. HCl

Abstract

Equilibrium partial pressures of HCl have been measured at 25°C over concentrated solutions containing the ions H + , Cl −, Mg 2+, NH 4 +, A1 3+, SO 4 2−, ClO 4 −, CH 3SO 3 −, and those of the alkali metals. Measurements agree closely with values predicted using a Henry's Law constant of 2.04 × 10 6mol 2kg −2atm −1 for the reaction HCl ( g) = H ( aq.) + + Cl ( aq.) −, and the Pitzer activity coefficient model. The following parameter values have been estimated for the model using the partial pressure and other thermodynamic data: θ H, Rb , −0.0120; ψ H, Rb, Cl , −0.012; θ H, NH 4 ,−0.01; ψ H, NH 4, Cl , −0.009; ψ H,NH 4,Br , −0.0104.