Solve the following problem

Question

A 0.43 mole of salicylic acid is mixed with 0.12 mole of acetic anhydride in order to synthesize Aspirin, if the actual weight of the final product which is Aspirin is equal to 13.2 g. Calculate the percentage yield (% yield).

Mwt of Aspirin = 180.16 g/mol

Answer 1

Percentage yield is the actual amount you got (13.2g) divided by the maximum possible amount (i.e. if the reaction had gone perfectly, how much would you have gotten).

In our case, the reaction is:

(1 Salicylic Acid) + (1 Acetic Anhydride) = (1 Acetylsalicylic Acid) + (1 Acetic Acid)

Since the reactant ratio is one to one, whichever one we have less of (in this case, the 0.12 mole of acetic anhydride) is the limiting reactant. And, we can see from our reaction equation that there should be one mole of Acetylsalicylic acid for each mole of acetic anhydride, so the maximum possible yield would be 0.12 mole of acetylsalicylic acid.

The molar mass of acetylsalicylic acid is 180.158 g/mol, so our theoretical yield is 21.61896 g. Since in reality, we only got 13.2g, that means our yield was 13.2/21.61896, or 61.06%