Standard enthalpies of formation of KCaH3−xFx with x = 1, 1.5, 2, 2.5

The standard enthalpies of formation of KCaH3−xFx with x=1, 1.5, 2, 2.5 were determined by calorimetry using their reaction with hydrochloric acid aqueous solution (0.5 M HCl): ΔfH0 (KCaH2F, cr, 298 K)=−(874±38) kJ mol−1ΔfH0 (KCaH1.5F1.5, cr, 298 K)=−(1092±5) kJ mol−1ΔfH0 (KCaHF2, cr, 298 K)=−(1305±16) kJ mol−1ΔfH0 (KCaH0.5F2.5, cr, 298 K)=−(1524±12) kJ mol−1The standard enthalpy of formation of KCaH3 was estimated on the basis of the experimental measurements and on the value for potassium–calcium fluoride (KCaF3) noted in the literature: ΔfH0 (KCaH3, cr, 298 K)=−(442±38) kJ mol−1These results show that hydride compounds are less stable than fluoride homologous.