Compressibility and partial molar volumes in the water-N,N-dimethylformamide system

Abstract

The compressibility coefficients k = (v0 − v)/v0 of the water-N,N-dimethylformamide (DMFA) binary system were measured over the whole concentration range at 278–323 K and pressures up to 100 MPa. The partial molar compressibility coefficients and volumes of the components at the state parameters specified were calculated. At all pressures, the k = f(x) (x is the mole fraction of DMFA) dependences contained minima, which shifted toward lower DMFA concentrations as the temperature increased. The partial molar volume of water at infinite dilution in DMFA \((\bar V_1^\infty )\) had a weak pressure dependence. The \(\bar V_2 = f(x)\) dependence passed a deep minimum at x ∼ 0.05. The depth of the minimum increased as the pressure grew or temperature lowered.