Question

A student reacts 89g of salicylic acid with 21 ml of acetic anhydride producing 11.3g of acetyl salicylic acid. what is the percent yield of the reaction?

Answer 1

The chemical equation would be written as:

C7H6O3 + C4H6O3 –> C9H8O4 +C2H4O2

First, we need to determine the limiting reactant by converting them into moles. After, we use the amount of limiting of reactant to determine the theoretical yield.

89g of salicylic acid ( 1 mol / 138.13 g ) = 0.644 mol
21 ml of acetic anhydride ( 1.02 g / mL) ( 1 mol / 102.09 g ) = 0.2098 mol

Therefore, the limiting reactant would be the acetic anhydride as it is th consumed completely. 

0.2098 mol acetic anhydride ( 1 mol C9H8O4 / 1 mol acetic anhydride) ( 180.157 g / 1 mol ) = 37.80 g C9H8O4

Percent yield = 11.3 / 37.80 x 100 = 29.89%