The first step in the industrial recovery of zinc from the zinc sulfide ore is roasting, that is, conversion of ZnS to ZnO by heating: 2ZnS (s) + 302 (g) - 2ZnO (s) + 2S02 (g) AH--879 kJ Calculate the heat released (in kJ) per gram of ZnS roasted.

In this item, we the given that the heat released for every 2 mols of ZnS is 879 kJ. The amount of ZnS in grams is calculated below,

amount of ZnS = (2 mols ZnS) x (97.474 g/mol)

= 194.9 g ZnS

The heat released per gram of ZnS is calculated by dividing 879 kJ by the amount in grams.

heat released = 879 kJ/194.9 g

heat released = 4.5 kJ/g