Question

1. write out the balanced equation for the reaction between salicylic aic and acetic anhydride.

2.calculate the percent yield for the above reaction if the amount of aspirin obtained was .301g from the amount of acid you started with (1.131g)

3. calculate the theoretical yield of aspirin if you start with 2.687g of salicylic acid and an excess of acetic anhydride.

Answer 1

1.C7H6O3+ C4H6O3 --------------> C9H8O4 + CH3COOH

no of moles of salicylic acid = W/G.M.Wt

                                              = 1.131/138.13   = 0.00818moles

1 mole of salicylic acid react with acetic anhydride to gives1 mole of asprine

0.00818 mole of salicylic acid react with acetic anhydride gives 0.00818 moles of asprine

molar mass of asprine = no of moles * gram molar mass

                                       = 0.00818*180   = 1.4724 g

2. paercentage yield   = actual yield*100/theoritical yield

                                  = 0.301*100/1.4724   = 20.44%

3.

C7H6O3+ C4H6O3 --------------> C9H8O4 + CH3COOH

no of moles of salicylic acid = W/G.M.Wt

                                              = 2.687/138.13   = 0.0194moles

1 mole of salicylic acid react with acetic anhydride to gives1 mole of asprine

0.0194 mole of salicylic acid react with acetic anhydride to gives 0.0194 mole of asprine

mass of asprine = no of moles * gram molar mass

                           = 0.0194*180   = 3.492g

theoritical yield = 3.492g