Equilibrium Vapor Pressure Measurements for the n‐Alcohols in the Temperature Range from −30 °C to + 30 °C

Abstract

AbstractWe measured the equilibrium vapor pressures pc ranging from 240 mmHg for methanol down to 5 · 10−3 mmHg for n‐hexanol, using capacitance pressure transducers. Good agreement is observed between literature data obtained by mercury manometers and our data in the ranges of overlap. Our data are found to be well described by the empirical Dupré‐Rankine formula. We analysed the thermodynamic basis of this relation and found its parameters to be interrelated. Once a reference temperature is chosen the number of adjustable parameters is reduced by one. The remaining parameters are physically relevant quantities, the molar vaporization enthalpy ΔHmv, and the difference of the molar specific heats of vapor and liquid phase ΔCmp. We evaluated these quantities from our measurements, and we give an overall fit of a combination of literature data and ours ranging from the boiling point to − 30 °C.