Experiments on Vapor Pressure of KCl at Different Molar Fractions in Mixtures of KCl+K2SO4

The objective of this paper is to measure the vapor pressure of potassium chloride (KCl) in its mixture with potassium sulfate (K2SO4). Evaporation behavior of pure salts of KCl, K2SO4, and their mixtures at different molar fractions were examined using a simultaneous thermogravi-metric analyzer (STA) at different temperatures with a pair of crucibles (outer: platinum; inner: alumina). The dependence of the vapor pressure of KCl on its molar fraction in mixtures of KCl + K2SO4 was obtained on the basis of relative pressure. Results show that vapor pressure of KCl is increased to 1.2 times when a small amount of K2SO4 (molar fraction from 0.05 to 0.20) is added. Evaporation of KCl will be inhibited by K2SO4 when the molar fraction of K2SO4 is higher than 0.27, which is its fraction in the eutectic system of KCl + K2SO4. Vapor pressure of KCl decreases significantly with increasing molar fractions of K2SO4 at its inhibition scope.

Automated summary

This study experimentally confirmed that the vapor pressure of KCl increases when its molar fraction in KCl + K2SO4 mixtures ranges from 0.05 to 0.20, and the evaporation of KCl is inhibited by K2SO4 when its molar fraction exceeds 0.27.