Chemistry - General Principles and Processes of Isolation of Metals Question with Solution | TestHub

The standard free energies of formation$\left(\mathrm{\Delta }{\mathrm{G}}_{\mathrm{f}}^{\mathrm{o}}\right)$of most of the sulphides are greater than those of$\mathrm{C}{\mathrm{S}}_2$and${\mathrm{H}}_2\mathrm{S}$. Hence, neither carbon nor hydrogen can reduce metal sulphides to metal. The standard free energies of formation of oxides are much lower than those of$\mathrm{S}{\mathrm{O}}_2$. Therefore, oxidation of metal sulphides to metal oxides is thermodynamically favourable. Hence sulphide ore is roasted to the oxide before reduction.