Measurements of the Vapour Pressures and Critical Data of Ammonium Halides

Abstract

AbstractIn order to determine the vapour‐pressure curve and the critical constants of ammonium halides, a high pressure autoclave was built for operation to 2000 bars and temperatures to 900°C. The highly corrosive ammonium salts are contained in internal cells made from gold‐platinum alloy or sapphire. Different types of such internal cells can be introduced into the autoclave enabling optical, conductivity, and PVT‐measurements of the gaseous and liquid phases to be made.Measured values for the vapour‐pressure curve of NH4Cl are reported. The critical temperature and critical pressure of NH4Cl are determined to be 882 ± 15°C and 1635 ± 20 bar respectively. The value 0.5 which is obtained for the critical exponent β of NH4Cl is compared with β‐values of other substances.