Subjecting a chromium sample (mass fraction of impurities 2 × 10−4) to chlorination in a calorimetric bomb with a microfurnace for sample heating made it possible to determine the standard molar change of energy at 298.15 K for the reaction: Cr(cubic) + 1.5Cl2(g) = CrCl3(hexagonal). The standard molar enthalpy of formation of CrCl3(hexagonal) at 298.15 K was calculated to be −(544.4±1.4) kJ·mol−1. (Here and in the paper uncertainties are given for a 95 per cent confidence interval.)

Subjecting high-purity metallic cobalt (mass-fraction impurity not exceeding 2 × 10−4) to chlorination in a nickel calorimetric bomb with a microfurnace for sample heating made it possible to determine the standard molar change of energy at 298.15 K for the reaction: Co(α) + Cl2(g) = CoCl2(cr). The standard molar enthalpy of formation of CoCl2(cr) was calculated to be −(311.07 ± 0.29) kJ · mol−1. (Here and elsewhere in the paper uncertainties are given for a 95 per cent confidence interval.)

Subjecting high-purity nickel metal (mass fraction of impurities < 6 × 10−5) to chlorination in a calorimetric bomb with a microfurnace for sample heating made it possible to determine the standard molar change of internal energy at 298.15 K for the reaction: Ni(cub.) + Cl2(g) = NiCl2(hexagon.). The standard molar enthalpy of formation of NiCl2(hexagon.) at 298.15 K was calculated to be −(304.78 ± 0.16) kJ·mol−1. (Here and in the paper uncertainties are given for a 95 per cent confidence interval.)

Subjecting a chromium sample (mass fraction of impurities 2 × 10−4) to chlorination in a calorimetric bomb with a microfurnace for sample heating made it possible to determine the standard molar change of energy at 298.15 K for the reaction: Cr(cubic) + 1.5Cl2(g) = CrCl3(hexagonal). The standard molar enthalpy of formation of CrCl3(hexagonal) at 298.15 K was calculated to be −(544.4±1.4) kJ·mol−1. (Here and in the paper uncertainties are given for a 95 per cent confidence interval.)

Subjecting a high-purity niobium sample (total mass percentage of impurities was at most 5.7 × 10−3) to chlorination with gaseous chlorine in a calorimetric bomb made possible the measurement of the internal energy change at 298.15 K for the reaction: Nb(s) + 2.5Cl2(g) = NbCl5(s) Using the thus-found value, the enthalpy of formation of niobium pentachloride was found to be ΔHfo(NbCl5, s, 298.15 K) = −(797.34 ± 0.27) kJ·mol−1.

Die Änderung der inneren Energie bei 298.15 K für die Reaktion Nb( S ) + 2.5 C12 (g) = NbCl 5 ( s) wurde mit Nbhoher Reinheit in C12 ‐Atmosphäre kalorimetrisch gemessen.

Combustion calorimetry of tin (IV) and tin (II) oxides yielded the energies of the reactions: Sn(tetragonal)+O2(g) = SnO2(tetragonal) (1) SnO(tetragonal)+12O2(g) = SnO2(tetragonal) (2) and the enthalpies of formation of SnO2 and SnO were calculated. The results are: ΔH°f(SnO2, tetragonal, 298.15 K) = −(577.63±0.16)kJ mol− and ΔH°f(SnO, tetragonal, 298.15 K) = −(280.71±0.21)kJ mol−