Which of the following statements is always true about the limiting reactant in a chemical reaction?

• A. It is always present in the greatest initial amount.
• B. It determines the theoretical yield of the product.
• C. It is completely consumed when the reaction goes to completion.
• D. It is the reactant with the highest molar mass.

Answer: (C)

Verified step by step guidance

1. Understand the concept of the limiting reactant: it is the reactant that is completely consumed first in a chemical reaction, thus limiting the amount of product formed.
2. Analyze each statement in the problem: the limiting reactant is not necessarily the one present in the greatest initial amount, so that statement is not always true.
3. Recognize that the limiting reactant determines the theoretical yield of the product because the amount of product formed depends on the amount of limiting reactant available.
4. Note that the limiting reactant is always completely consumed when the reaction goes to completion, which means no excess of this reactant remains.
5. Understand that the limiting reactant is not necessarily the reactant with the highest molar mass; molar mass does not determine which reactant limits the reaction.