Molar Gibbs Energy of Formation of BaMo2O7(s) Using the Solid Oxide Galvanic Cell Method

Abstract

ΔfG°(BaMo2O7,s,T) has been determined using the emf technique. The cell used was: (−)Pt/(BaMo2O7(s)+BaMoO4(s)+MoO2(s))//CSZ//air (p(O2(g)=21.21 kPa)/Pt(+). The observed emfs in the temperature range 828–985 K could be represented byE=0.7663−4.953×10−4T(±0.001) V. The standard molar Gibbs energy of formation of BaMo2O7(s) was evaluated from emf values and the ΔfG°(T) of BaMoO4(s) and MoO2(s). The corresponding expression is given as ΔfG°(BaMo2O7,s,T)=−2269.7+0.6173T(±5.1) kJ mol−1. Using the required literature values, the ΔfH°(BaMo2O7,s, 298.15 K) was calculated by the second-law method and the corresponding value is −2291.2 kJ mol−1. The present study is the first experimental work for the determination of ΔfG°(BaMo2O7,s,T).