Electrical Conductivity Measurement for Estimation of Standard Gibbs Energy Change of Ternary Oxide Formation

Abstract

Electrical conductivity measurements are used here to estimate the Gibbs energy change for formation of ternary oxide from binary oxides. The theoretical background and the advantages of the present method are discussed. As a demonstration, the standard Gibbs energy change of the reaction, Sr 3 Cr 2 O 8 + 1/2Cr 2 O 3 + 5/4O 2 → 3SrCrO 4 was estimated by electrical conductivity measurements of two kinds of Sr 3 Cr 2 O 8 oxides, one equilibrated with Sr 3 Cr 2 O 8 and the other with Cr 2 O 3 . The standard Gibbs energy change of the reaction is obtained as ΔG°/kJ mol -1 = -409 + 0.252T (±10), 1323 ∼ 1373 K. The resulting value is in good agreement with that obtained by measurement of the equilibrium oxygen pressure using a solid oxygen concentration cell.