Question

Aspirin is produced by the reaction of salicylic acid (C7H6O3 . M = 138.1 g/mol) and acetic anhydride(C4H6O3, M = 102.1 g/mol). C7H6O3(s) + C4H6O3(l) → C9H8O4(s) + C2H4O2(l) If 2.04 g of C9H8O4 (M = 180.2 g/mol) is produced from the reaction of 3.00 g C7H6O3 and 5.40 g C4H6O3, what is the percent yield?

Answer 1

Answer – We are given, mass of C₇H₆O₃(s) = 3.00 g

mass of C₄H₆O₃(l) = 5.40 g , mass of C₉H₈O₄(s) = 2.04 g

reaction – C₇H₆O₃(s) + C₄H₆O₃(l) -----> C₉H₈O₄(s) + C₂H₄O₂(l)

First we need to calculate the moles of each reactant

Moles of C₇H₆O₃(s) = 3.00 g / 138.1 g.mol^-1 = 0.0217 moles

Moles of C₄H₆O₃(l) = 5.40 g / 102.1 g.mol^-1 = 0.0529 moles

Now we know the balanced reaction has 1:1 mole ratio for all, so

Moles of C₉H₈O₄(s) from C₇H₆O₃(s) = 0.0217 moles

And this is the lowest moles than other, so C₇H₆O₃(s) is limiting reactant and moles of C₉H₈O₄(s) = 0.0217 moles

So, theoretical yield of C₉H₈O₄(s) = 0.0217 moles * 180.2 g/mol

                                                       = 3.91 g

We know

Percent yield = actual yield / theoretical yield*100%

                     = 2.04 g / 3.9*1 g * 100 %

                     = 52.1 %