Question

Calculate the empirical and molecular formula of a compound containing 32% carbon, 4% hydrogen and rest oxygen. Its vapour density is 75.

Answer 1

Empirical formula = C₂H₃O₃ 

Empirical formula mass = 24 + 3 + 48 = 75 

Molecular mass = 2 x (Vapour density) 

= 2 x 75 

= 150

n = (Molecular mass) / (Empirical formula mass) 

= 150/75

= 2

Molecular formula = (Empirical formula)_n

Molecular formula = C₂H₃O₃ x 2 

Molecular formula = C₄H₆O₆