Question

Calculate the freezing point of a solution that contains 1.75 mol of nacl dissolved in 1.00 kg of water. be sure to enter the new freezing point, and not the freezing point depression.

Answer 1

In order to calculate the new freezing point, we must first find the depression. This is given by:

ΔT = Kf * b * i

where Kf is the cryscopic constant for the solvent, b is the molarity of the solution in moles per kilogram and i is the van't Hoff factor, which tells us how many ions will be released when a substance is dissolved. 

Kf = 1.853, b = 1.5, i = 2 (Na⁺ and Cl⁻)

ΔT = 5.5 °C

The new freezing point will be 0 + 5.5
5.5 °C