Question

How will adding NaCl affect the freezing point of a solution?

Answer 1

Answer is: adding NaCl will lower the freezing point of a solution.

A solution (in this example solution of sodium chloride) freezes at a lower temperature than does the pure solvent (deionized water).

The higher the solute concentration (sodium chloride), freezing point depression of the solution will be greater.

Equation describing the change in freezing point:  

ΔT = Kf · b · i.

ΔT - temperature change from pure solvent to solution.

Kf - the molal freezing point depression constant.

b -  molality (moles of solute per kilogram of solvent).

i - Van’t Hoff Factor.

Dissociation of sodium chloride in water: NaCl(aq) →  Na⁺(aq) + Cl⁻(aq).

Answer 2

Adding NaCl (salt) will lower the freezing point. Examples of this include salt water bodies like the ocean, and why salt is spread on roadways during snow and icy conditions.