Calculate the freezing point of a solution of 20.0 g methyl salicylate, C7H6O2, dissolved in 800 g of benzene, C6H6. Kf for benzene is 5.10°C /m and the freezing point is 5.50°C for benzene.

Question

A) -1.05°C
B) 1.05°C
C) 4.45°C
D) 6.54°C

Answer 1

moles = grams/molar mass.
Solve for moles methyl salicylate.

molality = moles/kg solvent
Solve for molality

delta T = Kf*m
Solve for delta T

freezing point = 5.50 - delta T.

Answer 2

4.45