Effect of high pressure and temperature on the volume properties of the liquid-phase mixture of {water (1) + formamide (2)}

Abstract

Compression, k = Δv/vo, was measured for the {water (1) + formamide (2)} binary mixture within the whole range of the component ratio at temperatures from 278.15 K to 323.15 K and pressure up to 100 MPa. Molar isothermal compressions, molar isobaric thermal expansions, isochoric coefficient of thermal pressure and internal pressure were calculated. Concentration dependences (from formamide content) of molar isothermal compressions for water + formamide mixtures at low pressure and temperature (close to 278.15 K) were featured with the minimum at x2 ≈ 0.1, which was smoothed over with both pressure and temperature increase. Molar isobaric thermal expansions of the mixture increased with the increase of formamide content in it at all state parameters; pressure increase resulted in temperature inversion in its concentration dependence, which shifted to the area of lower formamide (FA) concentration with the pressure increase. Isochoric coefficient of thermal pressure of the mixture drastically increased in the area of small FA additions. The temperature effect on the thermal pressure coefficient was opposite in the mixtures with high water and high formamide content. Calculated values for pure components were also compared.