Investigation of potassium sulphateacalcium sulphate binary system by Knudsen effusion mass spectrometry

Vaporisation studies of pure K2SO4 and mixtures of K2SO4 and CaSO4 in the quasi-binary K2SO4aCaSO4 system using Knudsen effusion mass spectrometry resulted in the determination of thermodynamic data. From the partial pressures of the gaseous species over the condensed phases it was possible to determine the sublimation enthalpyIsubH and the thermodynamic activities of the components. The sublimation enthalpy of K2SO4 agrees very well with that of two literature sources. For the first time the experimental data of activities of K2SO4 and CaSO4 in the binary system could confirm the theoretical studies.