Thermodynamics of Hydrochloric Acid in 80 Weight Percent 2-Methoxyethanol and 20 Weight Percent Water From 10 to 50 °C.

Abstract

Electromotive-force measurements of cells of the type Pt, H2|HCl(m) in 2-methoxyethanol + H2O|AgCl, Ag at nine temperatures ranging from 10 to 50 °C were used to derive (a) the standard emf of the cell in 80 weight percent 2-methoxyethanol (methylcellosolve), (b) the activity coefficient of HCl, (c) the relative partial molal enthalpy and heat capacity of HCl, and (d) the thermodynamic constants for the transfer of HCl from water to 80 weight percent methylcellosolve. The molality of the acid ranged from 0.006 to 0.106 mol kg-1. To obtain the standard emf it was necessary to correct for ion-pair formation and to use the extended terms of the Debye-Hiickel theory. The standard emf varied with temperature (t, °C) according to the equation . Vapor pressures and dielectric constants for this mixture were measured over the temperature range. At 25 °C the solvent has a vapor pressure of 2506.5 Nm-2 (18.8 mm Hg) and a dielectric constant of 31.5.