We’re being asked to determine the solution will have the lowest freezing point.

Recall that the freezing point of a solution is *lower* than that of the pure solvent and the ** change in freezing point (ΔT_{f})** is given by:

$\overline{){{\mathbf{\Delta T}}}_{{\mathbf{f}}}{\mathbf{=}}{{\mathbf{T}}}_{\mathbf{f}\mathbf{,}\mathbf{}\mathbf{pure}\mathbf{}\mathbf{solvent}}{\mathbf{-}}{{\mathbf{T}}}_{\mathbf{f}\mathbf{,}\mathbf{}\mathbf{solution}}}$

The ** change in freezing point** is also related to the molality of the solution:

$\overline{){{\mathbf{\Delta T}}}_{{\mathbf{f}}}{\mathbf{=}}{{\mathbf{imK}}}_{{\mathbf{f}}}}$

where:

**i** = van’t Hoff factor

**m** = molality of the solution (in m or mol/kg)

**K _{f}** = freezing point depression constant (in ˚C/m)

The solution with the highest change in freezing point (ΔT_{f}) will be the solution with the lowest freezing point.

Which of the following solutions will have the lowest freezing point? Input the appropriate letter.

A. 35.0 g of C_{3}H_{8}O in 250.0 g of ethanol (C_{2}H_{5}OH)

B. 35.0 g of C_{4}H_{10}O in 250.0 g of ethanol (C_{2}H_{5}OH)

C. 35.0 g of C_{2}H_{6}O_{2} in 250.0 g of ethanol (C_{2}H_{5}OH)