What is the freezing point of this solution?

Question

A solution is made by dissolving 54g of C₂H₆O₂ in 215g H₂O. Freezing point depression constant for water is 1.86 degrees C kg/mol

Answer 1

Colligative properties:

 

∆T = imK

∆T = change in freezing point = ?

i = van't Hoff factor = 1 for C2H6O2 (a non electrolyte; probably ethylene glycol, i.e. antifreeze)

m = molality = moles solute/kg solvent = 54g/62g/mol/0.215 kg = 4.05 m

K = freezing constant = 1.86

∆T = (1)(4.05)(1.86) = 7.5 degrees C

Freezing point of the solution would be -7.5 degrees C