Which of the following statements is true about limiting and excess reagents in a chemical reaction?

• A. The excess reagent determines the theoretical yield of the product.
• B. The excess reagent is always the one present in the smallest initial amount.
• C. Both the limiting and excess reagents are completely consumed during the reaction.
• D. The limiting reagent is completely consumed first and determines the maximum amount of product formed.

Answer: (D)

Verified step by step guidance

1. Understand the definitions: The limiting reagent is the reactant that is completely consumed first in a chemical reaction, limiting the amount of product formed. The excess reagent is the reactant that remains after the limiting reagent is used up.
2. Recognize that the limiting reagent determines the theoretical yield because the reaction cannot proceed once it is fully consumed, regardless of how much excess reagent remains.
3. Note that the excess reagent is not necessarily the one present in the smallest initial amount; it depends on the stoichiometric ratios in the balanced chemical equation.
4. Understand that only the limiting reagent is completely consumed during the reaction, while some amount of the excess reagent remains unreacted.
5. Conclude that the true statement is: 'The limiting reagent is completely consumed first and determines the maximum amount of product formed.'