Question

The equation for lowering the freezing point of a solvent is given in your manual. Given that the freezing point for the pure solvent is 79.4 °C, the molality is 0.1 m, and the freezing point depression constant is 6.9 °C/m, determine the freezing temperature for the naphthalene solution.

Answer 1

Answer:

The freezing point of the solution is 78.71 °C

Explanation:

Step 1: Data given

Freezing point for the pure solvent is 79.4 °C.

Molality = 0.1 molal

Freezing point depression = 6.9 °C/m

Step 2: Calculate freezing point of the solution

ΔT = i*Kb*m

⇒ with i = the van't Hoff factor: naphthalene = a non-electrolyte, which means that the van't Hoff factor for this solution will be 1

⇒ with Kb = the freezing point depression constant = 6.9 °C/m

⇒ m = the molality = 0.1 molal

ΔT = 1 * 6.9 * 0.1

ΔT = 0.69

Freezing point of the solution = 79.4 °C - 0.69 = 78.71 °C

The freezing point of the solution is 78.71 °C