Question

Assuming you start with 10.0 g of zinc and 10.0 g hydrochloric acid, identify the limiting reagent and determine what mass of the other will remain after the reaction runs to completion.

Answer 1

The balanced chemical reaction for the substances given would be as follows:

Zn + 2HCl = ZnCl2 + H2

We are given the amounts of the reactants used in the reaction. We use these amounts to determine which is the limiting and excess reactant. We do as follows:

10 g Zn (1 mol / 65.38 g) = 0.1530 mol
10 g HCl (1 mol / 36.46 g) =  0.2743 mol

From the the stoichiometric ratio which is 1 is to 2, the limiting reactant would be hydrochloric acid and the excess would be zinc metal.

Mass of zinc that remains = 0.1530 - (0.2743 / 2) = 0.0159 g Zn