Question

The freezing point of benzene is 5.5oC What is the freezing point of a solution of 5.00 g C10H8 in 444 g #5) of benzene. You will need to look up the freezing point depression constant for benzene in a reference book

Answer 1

Answer:

T° fussion solution =  5.09°C

Explanation:

Let's apply the colligative property of freezing point depression.

ΔT = Kf . m

We must determine molality of the solution (mol of solute / kg of solvent)

Mass of solvent → 444 g. If we convert to kg (/1000) = 0.444 kg

Let's convert the mass of solute to moles ( mass / molar mass)

5 g / 128 g / mol = 0.039 moles

Molality = 0.039 mol / 0.444 kg → 0.08 m

Kf for benzene is 5.07 °C/m

ΔT = T° fussion pure solvent - T° fussion solution

5.5°C - T° fussion solution = 5.07 °C/m . 0.08 m

T° fussion solution = 5.07 °C/m . 0.08 m - 5.5°C

T° fussion solution =  5.09°C