Heat Capacities of Aqueous Solutions of Glutaric and Malonic Acids

Abstract

Abstract Using a calorimeter composed of a Dewar vessel and a Beckmann thermometer, the specific heat capacities of aqueous solutions of glutaric and malonic acids were measured at 30 °C. Techniques for establishing the temperature gadient between the solution in the Dewar and the outer air bath were adopted. The partial molar heat capacities at infinite dilution were estimated assuming a relation of the form mφCp=bm+cm2. The contributions of the –CH2– and –COOH groups to the partial molar heat capacities in aqueous solution are roughly additive: for –CH2– a positive contribution and for –COOH a negative one. The Δ(=‾Cp2°–Cp2(pure state)) were also calculated and positive and negative values were obtained for Δ(–CH2–) and Δ(–COOH), respectively.