limiting reagents

Question

hydrogen gas can be produced from reacting hydrochloric acid with zinc. if 12.31 g of zinc are reacted with 17.15 g of HCl, which is the limiting reagent.

Answer 1

First write the balanced chemical reaction.

Zn (s) + 2 HCl (aq) → ZnCl₂ (aq) + H₂ (g)

Use stoichiometry to convert grams of each reactant to grams of H₂ gas. The reactant that produces LESS H₂ gas will be the limiting reagent.

12.31 g Zn x (1 mol Zn / 65.38 g Zn) x (1 mol H₂ / 1 mol Zn) x (2.02 g H₂ / 1 mol H₂) = 0.3803 g H₂

17.51 g HCl x (1 mol HCl / 36.46 g HCl) x (1 mol H₂ / 2 mol HCl) x (2.02 g H₂ / 1 mol H₂) = 0.4803 g H₂

From above, you can see that Zn produces less H₂ gas, therefore, it is the limiting reagent.