Mass-spectrometric determination of the thermodynamics of potassium hydroxide and minor potassium-containing species required in magnetohydrodynamic power systems

Article abstract of DOI:10.1016/0021-9614(82)90032-5

Thermodynamic properties were obtained for several potassium-containing species by means of a series of effusion-mass-spectrometric studies.These included vaporization and dissociation experiments for KOH(g) correlated by both second and third laws, and resulted in a recommended standard enthalpy of formation: ΔH⁰_f(298.15 K) = -(228.0+/-2.0) kJ*mol^-1.MHD electric-power calculations have previously been based on a ΔH⁰_f(298.15 K) of -(232.6+/-12.5) kJ*mol^-1.Of major importance to MHD is the reduction of the uncertainty to +/-2 kJ*mol^-1, which reduces the error limits in the computed power from up to 150 per cent to less than 25 per cent.An experimental standard entropy of (238.1+/-4.0) J*K^-1*mol^-1 was obtained from the second-law correlation for KOH(g).A dissociation energy of (261.9+/-4.0) kJ*mol^-1 for KO(g) to K(²S_1/2) and O(³P₂) ground-state atoms was obtained.This study also yielded a value of (193.3+/-16.0) kJ*mol^-1 for D₀(KH,g) to K(²S_1/2) and H ground-state atoms, the first reported thermochemical measurement.Second- and third-law calculations of the enthalpy of formation and atomization energy for K2O(g) yielded recommended values of -(155.5+/-12.0) kJ*mol^-1 and (581.6+/-12.0) kJ*mol^-1, respectively.