Thermochemistry of cobalt(II) chloride hydrates

Abstract

The dehydration of cobalt(II) chloride-6-hydrate (CoCl₂,6H₂O) was investigated. The results can be summarized as CoCl₂,nH₂O_(c)= CoCl₂,mH₂O_(c)+(n–m)H₂O_(v), where n is 6, 4, 2, 1; m is 4, 2, 1, and 0. The enthalpy and entropy of reaction were calculated from the behaviour of the dissociation pressure as a function of temperature. The enthalpy and entropy of formation were calculated from the thermodynamic values. Magnetic moments and spectra were determined. The probable structure of the hydrates are discussed on the basis of the chemical and physical evidence and the known structures.