Heats of dissociation of gaseous alkali earth dihydroxides

Abstract

Flame photometric observations on the resonance lines of the alkaline earth elements in hydrogen + oxygen + nitrogen flames have been used to show that the great bulk of such elements are combined in the form of gaseous dihydroxides, Ca(OH)₂, etc., and that failure to realize this in the past has led to erroneously high values for the energies of dissociation of the diatomic oxides, CaO, etc., which had been assumed to predominate. The heats of dissociation of Ca(OH)₂, Sr(OH)₂ and Ba(OH)₂ into an atom of alkaline earth and two hydroxyl groups, at 0°K, are found to be 217, 215 and 229 kcal mole^–1 respectively, all ±12 kcal mole^–1.