
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