Thermodynamic properties of gases in propellants. III. Equilibriums in N2H2-1,1-N2H2(CH3)2 and He(or N2)-N2H4-1,1-N2H2(CH3)2 systems

Abstract

Gas-and liquid-phase equilibria in 2 4, 1,1-N2H2(CHS)2, their mixtures, and the solubilities of He(g) and N2(g) in the liquid mixtures have been measured. Excess volume of mixing of the mixtures has been determined as a function of composition. AG°, AH0, and 50 of vaporization have been obtained for the pure liquids. The measurements of vapor pressure and of liquid and gas compositions for the binary liquids have yielded the excess molar thermodynamic properties. An equation of the form AH -Xixja + bx 1 + cxj) for the molar heat of solution in terms of the mole fractions, xi, has been shown to be very convenient and useful and accounts for deviations from regularity. In the dilute regions, this equation assumes the "regular" form AH = axix%. The solubilities of He(g) and N2(g) in the liquid mixtures were measured at various temperatures and pressures. It was found that the ternary "regular behavior" is obeyed for the dissolved gases and that the atmospheric solubility K (in mole fraction) follows the linear relationship log K = e + fxx in a wide terminal composition range. AG°, AH0, and AS0 of solution have been computed for He and N2 and have been closely estimated for Ar. The values of all the useful thermodynamic properties have been tabulated at convenient compositions of the liquid phase. Deviations from ideality have been briefly discussed from a molecular point of view.i.e., the observed vapor pressure of these compounds(1) E. T.