Aspirin is prepared by heating salicylic acid, C7H6O3, with acetic anhydride, C4H603. The other product produced is acetic acid, C2H402.

C7H6O3+C4H6)3->C9H8O4+C2H4O2
What is the theoretical yield in grams of aspirin, C9H8O4, when 2.00 grams of salicylic acid is heated with 4.00g of acetic anhydride? If the actual yield of aspirin is 2.10g, what is the percentage yield?

4 answers

This is a limiting reagent problem because amounts for BOTH reactants are given.
AH = acetic anhydride.
SA = salicylic acid
ASA = aspirin
mols AH = grams/molar mass = ?
mols SA = grams/molar mass = ?

Using the coefficients in the balanced equation, convert mols AH to mols of ASA.
Do the same and convert mols SA to mols ASA.
It is quite likely that the two values will not agree which means one of them is wrong; the correct value in limiting reagent problems is ALWAYS the smaller value and the reagent producing that value is the limiting reagent.
Now convert mols of the product to grams by g = mols x molar mass. This is the theoretical yield (TY).
The actual yield in the problem is given as 2.10g (AY).
%yield = (AY/TY)*100 = ?

;lij;kj;

71.3%

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