Question

Which aqueous solution has higher concentration, 1 molar or 1 molal solution of the same solute? Give reason.

Answer 1

1 molar aqueous solution has higher concentration than 1 molal solution. A molar solution contains one mole of solute in one litre of solution while one molal solution contains one mole of solute in 1000 g of solvent. If density of water is 1, then one mole of solute is present in 1000 mL of water in 1 molal solution while one mole of solute is present in less than 1000mL of water in 1 molar solution (1000 mL sol = amount of solute + amount of solvent). Thus 1 molar solution is more concentrated.