Final answer:
C. Hydrochloric acid is the limiting reagent in the reaction between hydrochloric acid and magnesium, as there is not enough HCl to completely react with the available magnesium according to the stoichiometric ratio in the balanced chemical equation.
Step-by-step explanation:
To determine the limiting reagent in a reaction between hydrochloric acid and magnesium, we need to compare the mole ratio of the reactants to their coefficients in the balanced chemical equation. The balanced equation for the reaction is:
Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)
From the balanced equation, we can see that 1 mole of magnesium requires 2 moles of hydrochloric acid to react completely. Using the molar masses of magnesium (24.305 g/mol) and hydrochloric acid (36.461 g/mol for each mole of HCl), let's calculate how many moles of each reactant we have:
- For magnesium: 100 g ÷ 24.305 g/mol = 4.115 moles of Mg
- For hydrochloric acid: 100 g ÷ 36.461 g/mol = 2.742 moles of HCl
Since the stoichiometric ratio requires 2 moles of HCl per mole of Mg, for 4.115 moles of Mg we would need 2 * 4.115 = 8.230 moles of HCl. However, we only have 2.742 moles of HCl, which is insufficient. Therefore, hydrochloric acid is the limiting reagent.
So, the correct answer is:
C. Hydrochloric acid