freezing point chem

Question

What is the freezing point of a water solution with the total volume of 1.00L, that is made by dissolving 95.7 grams of manganese(II) sulfate, MnSO4 in water? Assume that MnSO4 dissociates completely into ions when it dissolves and Kf for water is 1.86°C/M

Answer 1

The freezing point depression is given by ∆T = imK

∆T = change in freezing point = ?

i = van't Hoff factor = 2 for MnSO4 b/c it produces Mn²⁺ and SO₄^2- (2 particles)

m = molality = moles solute/kg solvent = 95.7 g x 1mol/151 g = 0.634 mol/1 kg = 0.634 m

K = freezing constant for water = 1.86

∆T = (2)(0.634)(1.86) = 2.36ºC

Freezing point of solution = -2.36ºC