Limiting Reactions

Question

Heating zinc sulfide in the presence of oxygen yields the following:

2 ZnS + 3 O₂ --> 2 ZnO + 2 SO₂

If 1.72 mol of ZnS is heated in the presence of 3.04 mol of O₂, which reactant will be used up?

Answer 1

One easy way to identify the limiting reactant is to divide all the reactants by their respective coefficient in the balanced equation, and which ever value is the least will be the limiting reactant.

For Zn, we have 1.72 mol / 2 = 0.86

For O₂, we have 3.04 mol / 3 = 1.01

Since 0.86 is less than 1.01, Zn is the limiting reactant and will be used up.