Find the excess reagent(s)

Question

Sulfur dioxide can be scrubbed from smokestack emissions with the following reaction:

2 SO2(g) + 2 CaCO3(s) + O2(g) → 2 CaSO4(s) + 2 CO2(g)

Based on this chemical equation, which reagent(s) should be the excess reagent(s) so that the most sulfur dioxide is scrubbed from the emissions?

Answer 1

2SO₂(g) + 2CaCO₃(s) + O₂(g) → 2CaSO₄(s) + 2CO₂(g) ... balanced equation

Since you are trying to get rid of the SO2 (scrubbing it), you would want all the other reactants to be in excess to be sure you don't run out of them before you scrub all of the SO2. Thus, the reagents that should be excess are ...

CaCO₃

O₂