Question

Calculate the theoretical yield of aspirin to be obtained in experiment, 2.0 grams of salicylic acid and 4.1 mL of acetic anhydride (density = 1.08g/mL).

Answer 1

number of mole = (given mass)/(molar mass)
molar mass of salicyclic acid = 138.1 g/mol
number of mole of salicyclic acid = 2/138.1
= 0.0145 mol

molar mass of acetic anhydride = 102.1 g/mol
number of mole of acetic anhydride = 4.1/102.1
= 0.04 mol

1 mol of salicyclic acid ewact with 1 mol of acetic anhydride
here we have less salicyclic acid
so, salicyclic acid is limiting reagent
number of mol of aspirin formed = number of mol of salicyclic acid used
= 0.0145 mol
molar mass of aspirin = 180.2 g/mol
mass of aspirin formed = (number of mol)*(molar mass of aspirin)
= 0.0145*180.2
= 2.6 g

Answer : 2.6 g