Partial molal volumes of fluorochemical gases in cyclohexane

Abstract

Partial molal volumes V₂ of fluorochemical gases in cyclohexane at 25°C and mole fractions less than 10^–3 were determined as follows: CF₄ 86; C₂F₆ 111; C₃F₈ 140; c-C₄F₃ 144; SF₆ 101; CClF₃ 77. Values of V₂ have been calculated by the equation, (v₂–v_2,b)(∂S₁/∂V)_T=–0.64 R In x₂.v₂,b is the molal volume of the gas at its boiling point. The right-hand member is the entropy of volume expansion, on the excess of the total partial molal entropy of solution over the dilution entropy, –R In x₂. The values so calculated agree well with measured values except for CClF₃, due possibly to its unsymmetrical force field.