A dew point technique for limiting activity coefficients in nonionic solutions

A new measurement technique for activity coefficients at infinite dilution has been developed involving the construction of a very dilute vapor phase and the accurate determination of its dew point. This method is especially applicable to systems of low solute relative volatility, precisely where other methods such as differential ebulliometry and headspace gas chromatography become less precise. Data are reported for γ∞ for N, N‐dimethylformamide, dimethylsulfoxide, and N‐methyl pyrrolidone in water over a range of temperatures.