Limiting Reactions

Question

4. A reaction such as the one shown here is often used to demonstrate a single replacement reaction.

3CuSO₄ (aq) + 2Fe (s) ---> 3Cu (s) + Fe₂(SO₄)₃(aq)

If you place 0.092 mol of iron filings in a solution containing 0.158 mol of CuSO_4, what is the limiting reactant?

How many moles of Cu will be formed?

Answer 1

An easy way to identify the limiting reactant is to simply divide the moles of each reactant by their corresponding coefficient in the balanced equation.

For Fe we have 0.092 mole / 2 = 0.046

For CuSO4 we have 0.158 mol / 3 = 0.0527

This tells us that Fe is limiting.

To determine moles of product formed, we always base this on the moles of limiting reactant, and then use dimensional analysis.

0.092 mol Fe x 3 mol Cu / 2 mol Fe = 0.138 moles Cu formed