In a chemical reaction, what is the limiting reagent?

• A. The reactant that is completely consumed first, limiting the amount of product formed.
• B. The product that is formed in the smallest quantity.
• C. The reactant that remains after the reaction is complete.
• D. The reactant that is present in the greatest amount.

Answer: (A)

Verified step by step guidance

1. Identify the balanced chemical equation for the reaction. This will provide the stoichiometric ratios of the reactants and products.
2. Determine the initial amounts (in moles) of each reactant available for the reaction. This can be done using the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).
3. Using the stoichiometric ratios from the balanced equation, calculate the amount of product that can be formed from each reactant. This involves using the mole ratio from the balanced equation to convert moles of reactant to moles of product.
4. Compare the calculated amounts of product from each reactant. The reactant that produces the least amount of product is the limiting reagent.
5. The limiting reagent is the reactant that is completely consumed first, thus determining the maximum amount of product that can be formed in the reaction.