I have to find the theoretical yield of acetylsalicylic acid in the exeriment?

I used 5.0 mL acetic anhydride which is about 5.40 grams.

When I calculated the theoretical yield, I got 9.53 grams. Is this number correct?

2 answers

mols acetic anhydride = grams/molar mass
g acetylsalicylic acid = mols x molar mass.
Now that I've read your second post, what I wrote in my first response may or may not be correct. This is a limiting reagent problem. Go from there. And in the future, post ALL of the problem, not just part of it.