Gibbs' Energy of Formation of Nickel Orthosilicate (Ni2SiO4)

Abstract

Two solid state galvanic cells: Pt, Ni + Ni 2 Si0 4 + Si0 2 /(Y 2 0 3 )Zr0 2 /Ni + + NiO, Pt (I) and Pt, Ni + Ni 2 Si0 4 + Si0 2 /CaF 2 /Ni + + NiO, Pt (II) have been employed for the determination of the Gibbs' energy of formation of nickel orthosilicate (Ni 2 Si0 4 ) from nickel oxide and quartz. The emf of cell (I) was reversible and reproducible in the temperature range 925 to 1375K whereas emf of cell (II) drifted with time and changed polarity. From the results of cell (I), the Gibbs' energy of formation of nickel silicate is obtained as, 2NiO (r.s.) + Si0 2 (quartz) -> Ni 2 Si0 4 (olivine)