Practice question
Question
A solution of H₂SO₄ has a molarity of 0.5 M and a density of 1.02 g/mL. What is its molality? (Molar mass: H₂SO₄ = 98 g/mol)
Explanation
Mass of 1 L solution = 1000 × 1.02 = 1020 g. Mass of H₂SO₄ = 0.5 × 98 = 49 g. Mass of water = 1020 − 49 = 971 g = 0.971 kg. Molality = 0.5 / 0.971 ≈ 0.515 m.