For the theoretical yield, I used the mass of acetic anhydride. Was I supposed to use the mass of salicylic acid (which was 2.00 g) instead?

acetic anhydride + salicylic acid ---> acetic acid +acetylsalicylic acid

To determine the theoretical yield, you should use the stoichiometry of the balanced chemical equation and the limiting reagent. In this case, the balanced chemical equation is:

acetic anhydride + salicylic acid → acetic acid + acetylsalicylic acid

You will need to determine which reagent is the limiting reagent, i.e., the one that is completely consumed, and use its mass to calculate the theoretical yield.

If you used the mass of acetic anhydride, then you likely used the correct reagent to determine the theoretical yield. However, without knowing the masses of both acetic anhydride and salicylic acid, it's difficult to determine if you used the correct mass.

To determine the theoretical yield of a reaction, you need to use the stoichiometry of the reaction and the limiting reagent. In this case, the reaction is the reaction between acetic anhydride and salicylic acid to produce acetic acid and acetylsalicylic acid.

To determine the theoretical yield, you need to identify the limiting reagent, which is the reactant that is completely consumed in the reaction and determines the maximum amount of product that can be formed. The stoichiometry of the balanced equation will help you determine the ratio between the limiting reagent and the product.

In this reaction, the reactant that is completely consumed is the limiting reagent. To determine the limiting reagent, compare the number of moles of each reactant to the stoichiometric ratio given in the balanced equation.

For example, if the balanced equation is:

acetic anhydride + salicylic acid --> acetic acid + acetylsalicylic acid

and the stoichiometric ratio is 1:1, it means that one mole of acetic anhydride reacts with one mole of salicylic acid to produce one mole of acetic acid and one mole of acetylsalicylic acid.

To determine the moles of each reactant, divide the mass of each reactant (in grams) by their respective molar masses (in grams/mole).

Once you have determined the moles of each reactant, compare the mole ratio between the two reactants. The reactant with the smaller mole ratio is the limiting reagent.

Once you have identified the limiting reagent, you can use its moles and the stoichiometry of the balanced equation to calculate the theoretical yield of the product.

In your case, if you used the mass of acetic anhydride to calculate the theoretical yield, you need to check whether acetic anhydride is the limiting reagent or not by going through the steps mentioned above. If it is not the limiting reagent, you should have used the mass of salicylic acid to calculate the theoretical yield.

I hope this explanation helps you understand how to determine the correct mass to use for calculating the theoretical yield in this reaction.