Question

Aspririn (C₉H₈O₄) is produced from salicylic acid (C₇H₆O₃) and acetic anhydride (C₄H₆O₃):

C₇H₆O₃ + C₄H₆O₃ ===> C₉H₈O₄ + HC₂H₃O₂

How much salicylic acid (in kg) would be required to produce 1.5*10² kg of aspirin if only 80% of the salicylic acid is converted to aspirin?

Answer 1

Molar mass of C9H8O4,
MM = 9*MM(C) + 8*MM(H) + 4*MM(O)
= 9*12.01 + 8*1.008 + 4*16.0
= 180.154 g/mol

mass of C9H8O4 = 150000 g
mol of C9H8O4 = (mass)/(molar mass)
= 150000/180.154
= 832.621 mol

use:
% yield = actual yield * 100 / theoretical yield
80 = 832.621*100 / theoretical yield
theoretical yield = 1041 mol

According to balanced equation
mol of C7H6O3 required = moles of C9H8O4
= 1041 mol


Molar mass of C7H6O3,
MM = 7*MM(C) + 6*MM(H) + 3*MM(O)
= 7*12.01 + 6*1.008 + 3*16.0
= 138.118 g/mol


mass of C7H6O3 = number of mol * molar mass
= 1041*138.118
= 1.44*10^5 g
= 1.44*10^2 Kg
= 144 Kg

Answer: 144 Kg