Question

Calculate (to the nearest 0.1 u) the formula mass of these compounds.(a) ibuprofen, C13H18O2(b) acetaminophen, C8H9NO2(c) penicillin, C16H18N2O4S

Answer 1

a) Ibuprofen ≈ 206.3 g/ mol

b) acetaminophen ≈ 151.2 g/mol

(c) penicillin ≈ 334.4 g/mol

Procedure

To solve this question, we need to add the molecular weight of each element multiplied by the number of atoms as follows:

Data

Carbon = 12.011 u

Oxygen = 15.999 u

Hydrogen = 1.00784 u

Nitrogen = 14.0067 u

Sulfur = 32.065 u

a) Ibuprofen

12.011 x 13 + 1.00784 x 18 + 15.999 x 2 =206.2821 ≈ 206.3 g/ mol

b) acetaminophen

12.011 x 8 + 1.00784 x 9 + 14.0067 + 15.999 x 2 =151.1633 ≈ 151.2 g/mol

(c) penicillin

12.011 x 16 + 1.00784 x 18 + 14.0067 x 2 + 15.999 x 4 + 32.065 =334.3915 ≈ 334.4 g/mol