Standard molar Gibbs free energy of formation of PbO(s) over a wide temperature range from EMF measurements

The EMF of the following galvanic cells, (Cell(I))Kanthal,Re,Pb,PbO∣CSZ∣O2 (1 atm.),Pt(Cell(II))Kanthal,Re,Pb,PbO∣CSZ∣O2(1 atm.),RuO2,Ptwere measured as a function of temperature. With O2 (1 atm.), RuO2 as the reference electrode, measurements were possible at low temperatures close to the melting point of Pb. Standard Gibbs energy of formation, ΔfG0m〈β-PbO〉 was calculated from the emf measurements made over a wide range of temperature (612–1111 K) and is given by the expression: ΔfG0m〈β-PbO〉±0.10 kJ=−218.98+0.09963T. A third law treatment of the data yielded a value of −218.08 ± 0.07 kJ mol−1 for the enthalpy of formation of PbO(s) at 298.15 K, ΔfH0m〈β-PbO〉 which is in excellent agreement with second law estimate of −218.07 ± 0.07 kJ mol−1.