Question

Hydrochloric acid reacts with calcium to form hydrogen and calcium chloride. if 100 grams of hydrochloric acid reacts with 100 grams of calcium, what is the limiting reactant? 2hcl ca → cacl2 h2 calcium hydrogen calcium chloride hydrochloric acid

Answer 1

Answer: hydrochloric acid

Explanation: $2HCl+Ca\rightarrow CaCl_2+H_2$

As can be seen from the chemical equation, 2 moles of hydrochloric acid react with 1 mole of calcium.

According to mole concept, 1 mole of every substance weighs equal to its molar mass.

Thus $2\times 36.5=73 g$ of of hydrochloric acid reacts with 40 g of calcium.

100 g of hydrochloric acid react with=$\frac{40}{73}\times 100=54.79 g$of calcium

Thus HCl is the limiting reagent as it limits the formation of product and calcium is the excess reagent as (100-54.79)=45.21 g is left unreacted.

Answer 2

The balanced chemical reaction is:

2HCl + Ca = CaCl2 + H2

We are given the amount of the reactants to be used for the reaction. These values will be the starting point of our calculations.

100 g HCl ( 1 mol HCl / 36.46 g HCl ) = 2.74 mol HCl

100 g Ca ( 1 mol Ca / 40.08 g ) = 2.08 mol Ca

From the reaction, the mole ratio of the reactants is 2:1 where every 2 moles of hydrochloric acid, 1 mole of calcium is required. Therefore, the limiting reactant for this case is calcium.