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
