Experiments on Vapor Pressure of KCl at Different Molar Fractions in Mixtures of KCl + K 2 SO 4 .

The objective of this paper is to measure the vapor pressure of potassium chloride (KCl) in its mixture with potassium sulfate (K 2 SO 4 ). Evaporation behavior of pure salts of KCl, K 2 SO 4 , and their mixtures at different molar fractions were examined using a simultaneous thermogravimetric 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 + K 2 SO 4 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 K 2 SO 4 (molar fraction from 0.05 to 0.20) is added. Evaporation of KCl will be inhibited by K 2 SO 4 when the molar fraction of K 2 SO 4 is higher than 0.27, which is its fraction in the eutectic system of KCl + K 2 SO 4 . Vapor pressure of KCl decreases significantly with increasing molar fractions of K 2 SO 4 at its inhibition scope.