Aspirin can be made in the laboratory by reacting acetic anhydride (C₄H₆O₃) with salicylic acid (C₇H₆O₃) to form aspirin (C₉H₈O₄) and acetic acid (C₂H₄O₂). The balanced equation is: C₄H₆O₃ + C₇H₆O₃ → C₉H₈O₄ + C₂H₄O₂ In a laboratory synthesis, a student begins with 6.00 mL of acetic anhydride (density= 1.08 g/ mL) and 2.50 g of salicylic acid. Once the reaction is complete, the student collects 1.82 g of aspirin. Determine the limiting reactant, theoretical yield of aspirin, and percent yield forthe reaction.

Key Concepts

Limiting Reactant

The limiting reactant is the substance that is completely consumed first in a chemical reaction, thus determining the maximum amount of product that can be formed. To identify it, one must compare the mole ratios of the reactants based on the balanced chemical equation. The reactant that produces the least amount of product is the limiting reactant, which directly affects the yield of the desired product.

Theoretical Yield

The theoretical yield is the maximum amount of product that can be generated from a given amount of reactants, as calculated from the balanced chemical equation. It assumes complete conversion of the limiting reactant into the product without any losses. This value is essential for determining the efficiency of a reaction and is typically expressed in grams or moles.

Percent Yield

Percent yield is a measure of the efficiency of a chemical reaction, calculated by dividing the actual yield of the product obtained from the experiment by the theoretical yield, then multiplying by 100. It provides insight into how effectively the reactants were converted into products and can indicate potential losses due to side reactions, incomplete reactions, or experimental errors.