Question

In the reaction `C_2H_4(g)+3O_2(g)->2CO_2(g)+2H_2O(g)`, if 2.70 mol `C_2H_4` is reacted with 6.30 mol `O_2`, what is the limiting reagent?

Answer 1

Clearly, oxygen gas is the LIMITING reagent.

Explanation:

Why can I say "clearly"? The stoichiometric equation you have posted shows that 1 mole of ethylene requires 3 moles of oxygen gas (the diatomic molecule).

Thus, 2.70 mol ethylene requires 8.10 mol dioxygen gas for complete reaction. How do I know this? I know this because of the given reaction stoichiometry. In the absence of stoichiometric oxygen, incomplete carbon combustion may occur to give `C` (as soot), or `C-=O`, as oxidation products (or both), but I assume complete combustion, and only consider the reaction AS WRITTEN.