Saturated vapour pressure of potassium sulphate

Abstract

The saturated vapour pressure of K₂SO₄ has been measured by a combination of the Knudsen effusion and transpiration techniques, over the temperature range 1180–1668 K. Between 1180 and 1342 K (the melting point of K₂SO₄), the vapour pressures may be expressed by the equation log₁₀(P/atm)=–1.47±0.09 × 10⁴/T K+6.84±0.69, the mean heat of sublimation being 67.3±4.0 kcal/mol. Between 1342 and 1668 K the vapour pressures follow the equation log₁₀(P/atm)=–1.27±0.09 × 10⁴/T K+5.37±0.69, the mean heat of evaporation being 58.3±4.1 kcal/mol. Extrapolation to 1 atm gives a theoretical boiling point of 2370±100 K and an entropy of evaporation at the boiling point of 24.6±2.2 cal/mol K.