Assume you used 0.200g of salicylic acid and 0.480mL of acetic anhydride, and you obtain 0.152g of pure, recrystallized, dry aspirin. Calculate the percent yield.

Answer 1

Write and balance the equation; however I think the ratio is 1:1 for reactants and products.
When amounts are given for both reactants you know it is a limiting reagent problem.
mols salicylic acid = grams/molar mass
Look up the density of acetic anhydride and determine grams acetic anhydride. Then mass = volume x density and mols = grams/molar mass

Convert mols SA to mols product.
Convert mols of AH to mols product.
It is likely that these two values will not be the same which means one of them is wrong; the correct answer in limiting reagent problems is ALWAYS the smaller value.
Then grams = mols x molar mass. This is the theoretical yield. We will call that TY.
%yield = (actual yield/TY)*100 = ?