To determine which statement correctly describes the actual yield and the theoretical yield of a reaction, let's analyze each option:
1. Option 1: "The actual yield is calculated from the reactant amounts, but the theoretical yield must be measured for each instance of a reaction."
- This is incorrect because the actual yield is measured from the amount of product obtained experimentally, and the theoretical yield is calculated based on the reactant amounts using stoichiometry.
2. Option 2: "The actual yield is calculated from the amount of the limiting reactant, and the theoretical yield is calculated from the amount of the excess reactant."
- This is incorrect because the theoretical yield is always calculated based on the limiting reactant, not the excess reactant. The actual yield is the measured amount of product obtained.
3. Option 3: "The actual yield depends on the reaction conditions, but the theoretical yield varies only with reactant amounts."
- This is correct. Actual yield is affected by various factors including reaction conditions (such as temperature, pressure, and purity of reactants). The theoretical yield, on the other hand, is a stoichiometric calculation based on the amounts of reactants, assuming perfect conditions where the reaction goes to completion.
4. Option 4: "The actual yield represents the maximum yield possible, and the theoretical yield assumes perfect reaction conditions."
- This is incorrect because the theoretical yield represents the maximum amount of product that can be formed from the given reactants under perfect conditions, while the actual yield is what is actually obtained experimentally.
Based on the analysis:
The correct statement is: "The actual yield depends on the reaction conditions, but the theoretical yield varies only with reactant amounts."
