Question

What is the limiting reactant when 31.5 g of
CuO are exposed to 2.7 g of H2 according to
the equation
CuO(s) + H2(g) −→ Cu(s) + H2O(g) ?
1. Neither is limiting.
2. Unable to determine.
3. CuO
4. H

Answer 1

Convert 2.7 g H2 to moles. moles = grams/molar mass
Convert 31.5 g CuO to moles the same way.

Using the coefficients in the balanced equation, convert moles H2 to moles Cu.
Do the same for CuO to moles Cu. You will obtain two answers and only one can be right; the correct one in limiting reagent problems is ALWAYS the smaller one and the reagent providing that number is the limiting reagent.

Answer 2

#3 is the answer, CuO is the limiting reactant