How many grams of acetic acid are formed as a by-product when 11.4 g of aspirin are synthesized?

Answer 1

I'll assume you are doing a common synthesis of asprin from salicylic acid and acetic anhydride.

The first thing we want to know is the balanced chemical equation. For a synthesis from salicyic acid, the equation is 1-to-1 because all of the coefficients are 1. In other words, the molar amount of asprin synthesized is equal to the molar amount of acetic acid produced (ideally--in practice, no reaction is perfect). The molar mass of acetylsalicylic acid (asprin) is 180.2 grams per mol. If we divide the mass produced by the molar mass, we get the molar amount of asprin synthesized (11.4/180.2=0.06 mols). Since acetic acid will be produced in equal molar amount to asprin, we also have 0.06 mols of acid. Multiplying this by the molar mass of acetic acid (60.05 g/M), we get 3.8 grams of acetic acid. Therefore, assuming ideal conditions, you have produced 3.8 grams of acetic acid as a by-product of your 11.4 grams of asprin. Hope this helps!