Question

A student performed an experiment to synthesize aspirin using 5 grams of salicylic acid and an excess of acetic anhydride. After the reaction was completed, the student collected 4.2 grams of aspirin. What is the percent yield of this experiment?

Answer 1

To calculate the percent yield, we first need to determine the theoretical yield, which is the maximum amount of product that can be formed from the given amount of reactants.The balanced chemical equation for the synthesis of aspirin is:C7H6O3  salicylic acid  + C4H6O3  acetic anhydride   C9H8O4  aspirin  + C2H4O2  acetic acid From the balanced equation, we can see that 1 mole of salicylic acid reacts with 1 mole of acetic anhydride to produce 1 mole of aspirin.First, we need to calculate the moles of salicylic acid used in the experiment:Moles of salicylic acid = mass / molar massThe molar mass of salicylic acid  C7H6O3  =  7  12.01  +  6  1.01  +  3  16.00  = 138.12 g/molMoles of salicylic acid = 5 g / 138.12 g/mol = 0.0362 molNow, we can calculate the theoretical yield of aspirin:Moles of aspirin = moles of salicylic acid  since they react in a 1:1 ratio  = 0.0362 molThe molar mass of aspirin  C9H8O4  =  9  12.01  +  8  1.01  +  4  16.00  = 180.16 g/molTheoretical yield of aspirin = moles of aspirin  molar mass of aspirin = 0.0362 mol  180.16 g/mol = 6.52 gNow we can calculate the percent yield:Percent yield =  actual yield / theoretical yield   100Percent yield =  4.2 g / 6.52 g   100 = 64.4%The percent yield of this experiment is 64.4%.