Chemistry - Thermodynamics - II Question with Solution | TestHub

For the reactions,

$2\mathrm{Z}\mathrm{n}\mathrm{S}\to 2\mathrm{Z}\mathrm{n}+{\mathrm{S}}_2;\mathrm{\Delta }\mathrm{G}°=+293\mathrm{J}$...(i)

$2\mathrm{Z}\mathrm{n}+{\mathrm{O}}_2\to 2\mathrm{Z}\mathrm{n}\mathrm{O};\mathrm{\Delta }\mathrm{G}°=-616\mathrm{J}$...(ii)

${\mathrm{S}}_2+2{\mathrm{O}}_2\to 2\mathrm{S}{\mathrm{O}}_2;\mathrm{\Delta }\mathrm{G}°=-408\mathrm{J}$...(iii)

The$\mathrm{\Delta }\mathrm{G}°$for the reaction,

$2\mathrm{Z}\mathrm{n}\mathrm{S}+3{\mathrm{O}}_2\to 2\mathrm{Z}\mathrm{n}\mathrm{O}+2\mathrm{S}{\mathrm{O}}_2$

can be obtained by adding equations. (i), (ii) and (iii)

So,$\mathrm{\Delta }\mathrm{G}°=293-616-408=-731\mathrm{J}$