Thermodynamics of the interaction of HCl with propan-2-ol in water at 278.15–338.15 K

Abstract

The emfs of cells Pt, H₂(g, p⁰)| HCl(m_E)| AgCl/Ag, and Pt, H₂(g, p⁰)| HCl(m_E), 2-PrOH(m_N)| AgCl/Ag have been measured at 10 K intervals from 278.15 to 338.15 K, where 2-PrOH refers to propan-2-ol, m_E= 0.005–0.1 mol kg^–1, and m_N= 0.2–0.7 mol kg^–1. The emf data were used to determine the salting-out constant, k_s, of 2-PrOH and the thermodynamic interaction parameters, ƒ_EN(g_EN, h_EN, s_EN, c_{P, EN}) of 2-PrOH with HCl in water at different temperatures. It has been shown that k_s > 0, g_EN > 0, h_EN > 0, s_EN > 0 and c_{P, EN} < 0 at all temperatures concerned (except for s_EN and h_EN which are negative at 328.15 and 338.15 K) and that s_EN and c_{P, EN} vary linearly with increasing temperature. A comparison of these thermodynamic parameters is made with those for HCl–PG (propane-1,2-diol) and HCl–GL (glycerol) pairs in water. The dependence of the parameters on the number of hydroxy groups in alcohol molecules has been interpreted on the basis of the group additivity model.