Question

How many grams of aspirin are produced if 83.4 g of salicylic acid is treated with excess acetic anhydride?

.................g

Answer 1

Asprin is made by the reaction of salicylic acid and acetic anhydride;

C₇H₆O₃ + C₄H₆O₃ $\to$ C₉H₈O₄ + CH₃CO₂H

Since acetic anhydride is in excess, salicylic acid is the limiting reagent here

Moles of Salicylic acid $=\dfrac{mass}{MM} = \dfrac{83.4g}{138.121g/mol}=0.6038mol$

Moles of aspirin produced;

From the balanced equation, the mole ratio is 1:1

Hence, moles of aspirin$=\dfrac{1}{1}x0.60382 mol$

Mass of aspirin;

Mass = moles x MM

= 0.60382 mol x 180.158g/mol

= 108.78g of aspirin is produced