Why is the percentage yield of the asprin synthesised less than 100%

Question

Why is the percentage yield of the asprin synthesised less than 100%

Answer 1

There are/could be many reasons. One reason is that some of the the aspirin that is made is hydrolyzed. Another is that the reaction is partially reversible. An additional reason is that one of the reactants was in limited supply. The temperature of the reaction may have been sub-optimal. There are other reasons as well.