Determination of the ionization constant of water between 100 to 200°C by emf measurements,with some derived thermodynamic quantities

The first experimentally derived values of the ionization constant of water and associated thermodynamic quantities, by emf measurements, are reported, within the range 100–200°C. The derived values of the ionization constant of pure water from these measurements support the findings obtained by purely thermochemical observations. The effects of a recalculation of the observed discrepancies, both in the heats of ionization and molal heat capacity, between emf measurements and thermochemical values at 25°C are also discussed, by an appraisal of the empirical methods that are available and that have been used for the treatment of experimental data. A method, producing a new family of equations based on theoretical-structural considerations, is also suggested for the behaviour of the ionization constant of water as a function of temperature. Values for the heats of ionization of water between 100 and 200°C are also proposed.