Question

Can someone explain how to do this? Consider the following equation: `"2ZnS"` + `"3O"_2` `rarr` `"2ZnO"` + `"2SO"_2` , ΔH° = - 878.2kJ. What is the enthalpy change when 0.96 g ZnO is produced?

Answer 1

When 0.96g of zinc oxide is produced, the enthalpy change is

-5.15 kJ.

2 moles ZnS produce 2 moles ZnO to give 878.2 kJ of energy which is released to the surroundings:

Convert moles to grams:

[ Ar (Zn) = 65.28 Ar (S) = 32.06 Ar (O) = 16]

2 x (65.28 + 32.06) g ZnS`rarr`2x (65.28 + 16 ) ZnO to give out 878.2 kJ

So

194.68g ZnS`rarr` 162.56g ZnO to give out 878.2 kJ of energy.

So 162.56 g of ZnO produces 878.2 kJ of energy

So 1g of ZnO produces 872.8/162.56 = 5.37 kJ of energy

So 0.96 g of ZnO will produce 5.37 x .96= 5.15 kJ of energy