Enthalpies of formation of the negative ions MnO, MnO and MnO as determined by the ion/molecule equilibrium method

Admixture of potassium chromate to manganese oxide has allowed us to generate measurable concentrations of the negative ions MnO , MnO , and MnO in the vapours over manganese oxide at 1300–1500 K. Equilibrium constants with the participation of these ions have been measured and the enthalpies of formation {Δ f H (MnO , 0 K) = (−266±13)kJmol −1 , δ f H ,(MnO , 0 K) = (−538±14) kJmol −1 , δ f H (MnO , 0 K) = (−669±17)kJ mol −1 }, dissociation energies and the electron affinity (EA) of MnO 2 {EA = 292kJ mol −1 } have been estimated. The use of manganese‐containing negative ions to measure the activity of manganese oxides is discussed.