4. Calculate the freezing point of a solution of 45.0 g of ethylene glycol (C2H6O2) dissolved in 250.0 g of water?

Answer 1

Colligative properties:

Freezing point depression: ∆T = imK

∆T = change in freezing point = ?

i = van't Hoff factor = # of particles = 1 for ethylene glycol since it doesn't ionize of dissociate

m = molality = moles solute/kg solvent = 45.0 g x 1mol/62g = 0.726 mol/0.250 kg = 2.90 molal

K = freezing point constant for water = 1.86º/m

∆T = (1)(2.90)(1.86) = 5.4º ... this is the freezing point depression, so freezing point of the new solution is...

0º - 5.4º = -5.4ºC because water normally freezes at 0ºC