Practice question
Question
A compound has a molar mass of 180 g/mol and contains 40% carbon, 6.67% hydrogen, and 53.33% oxygen. What is its molecular formula? (Atomic masses: C = 12, H = 1, O = 16)
Explanation
For 100 g: C = 40 g, H = 6.67 g, O = 53.33 g. Moles: C ≈ 3.33, H ≈ 6.67, O ≈ 3.33. Ratio = 1 : 2 : 1; empirical formula = CH₂O, mass = 30 g/mol. n = 180/30 = 6; molecular formula = C₆H₁₂O₆.