Studies of the Vaporization/Decomposition of Alkali Sulfates

Publisher Website
Google Scholar
Abstract
To complement a previous study of the vaporization behavior of , the vaporization of Li, Na, Rb, and Cs sulfates has been studied by mass spectrometry and the torsion‐effusion method to determine the total pressures, molecular weights, and compositions of the effusing vapors. Both molecular vaporization of and dissociation contribute to the vaporization flux. For Na, Rb, and Cs sulfates, the decomposition reaction is . From the difference between the measured total pressures and calculated decomposition pressures, the contributions attributable to molecular vaporization of , , and are about 37, 75, and 95% of the total pressures over the respective sulfates in the temperature ranges of our measurements. Vapor molecular weights determined from simultaneous torsion‐effusion and mass‐loss measurements are in close agreement with the compositions inferred from the pressure data. Decomposition of occurs by the reaction ; the reacts with the remaining to form a liquid solution phase of unknown activity. sublimation accounts for about 0.3% of the pressure over . The derived heats of sublimation in kilojoules per mole at 298 K were determined to be for , for , for , and for . Values of the entropies of the gaseous sulfate molecules were derived from slope heats and absolute pressures and are compared with values calculated from molecular constants.

This publication has 0 references indexed in Scilit: