Calculate the boiling point of a solution containing 0.5 mol of a solute per 400 ml of acetone (acetone density 786 g / l).

Decision.

Let’s find the mass of acetone.

m = ρ * V = 786 * 0.4 = 314 g = 0.3 kg;

according to Raoult’s law, an increase in the boiling point of a non-electrolyte solution:
Δt bale = E ∙ Cm = E ∙ n (sol. In-va) / m (r-la);

E – ebulioscopic constant, tabular value.

E acetone = 1.5;

Δt bale = E ∙ Cm = E ∙ n (sol. In-va) / m (r-la) = 1.5 ∙ 0.5 / 0.3 = 2.5 °;

tо – boiling point of acetone, tabular value.

tо = 56 °;

The boiling point of the solution: tboil = to + Δt boiling. = 56 + 2.5 = 58.5 ° C.

Answer: tboil = 58.5 ° C.