Freezing point Calculations.

Question

What is the freezing point of a solution of 12.0g of CCl4 dissolved in 750.0g of benzene? The freezing point of benzene is 5.48C  and Kf is 5.12 C/m

Answer 1

Hi Harleen,

 

Well the formula you need is

 

ΔT = K_f × m × i

 

K_f you're given directly.

 

m is the molality, which is moles of solute per kilogram of solvent. CCl₄ is the solute so calculate the moles of that and divide by the kg of benzene.

 

i is the Van 't Hoff factor, and since the solute is a molecular compound, i = 1.

 

Multiply them to get the change in temperature, and subtract that change from the normal freezing point of benzene.

 

Jim Scripko