Basicity And Redox Equilibria In Silicate Melts

The form of an equilibrium constant for a redox reaction in an open system is derived. The basicity does not directly enter into the equilibrium constant. Its influence is only through the ratio of the activity coefficients of the polyvalent ion in its various oxidation states. A physical model helpful in judging the direction of the change in the equilibrium in response to a change in basicity or temperature is discussed.