Thermodynamic properties of mixtures of alkanes differing in chain length. II. Vapour pressures

Abstract

A description is given of a micro‐method for the determination of vapour pressures at elevated temperatures. In this method the vapour over the solution is brought into thermodynamic equilibrium with that of the pure volatile component at a lower temperature. The pressure is indirectly determined by the accurate measurement of the difference in temperature between the solution and the pure volatile component.With this apparatus we have determined the vapour pressure of heptane in mixtures with dotriacontane at 73° C, and in mixtures with a polythene fraction at 109° C. In another apparatus the vapour pressure of 2,2,4‐trimethyl pentane‐hexadecane mixtures has been investigated at 24.9° C. The thermodynamic consequences of the heats of mixing and vapour pressures measured are discussed.