Abstract
A simple partition method using benzene has been found of practical value in determining the partial vapour pressure of HC1 over aqueous solutions containing also a second solute, the latter being insoluble in benzene, in regions of composition corresponding to the maximum concentration of HC1 in effluent gases permitted by factory regulations. The partition of hydrogen chloride between. water and benzene has been measured at 30Β° over a wide range of concentrations and over a lesser range at 40Β°. The data are correlated with other known partition data for this system and with published measurements of hydrogen chloride gas phase concentrations over benzene solutions at 20, 25, 30 and 40Β°. Over the molality range 7Β·2 Γ 10^β6^ to 2Β·73 Γ 10^β1^in benzene, the activity coefficient of hydrogen chloride in benzene has been shown to be unity, and to be unaffected by the presence of the water also in partition equilibrium. It is shown to be a theoretical possibility that combination of HCl with H~2~O in the benzene might cause the ratio of molality of HCl in benzene (Mβ²t) to activity of HCl in water (a~HCl~) to increase at dilutions greater than those investigated. The temperature dependence of the partition constant is represented over the temperature range 20β40Β° by the equation The difference of partial molar heat content of HCl in the two solvents at infinite dilution calculated from the equation is 13, 600 calorics per g. mol. Correspondingly the heat of solution of gaseous HCl in benzene at infinite dilution is 4660 calories per g. mol.