Question: If the freezing point of pure water is 0 °C, what will be the freezing point of a solution containing 1 mole of NaCl in 1 kg of water? (2023)

Options:

1. -1.86 °C
2. -3.72 °C
3. -2.26 °C
4. -0.93 °C

Correct Answer: -3.72 °C

Exam Year: 2023

Solution:

Freezing point depression = i * Kf * m = 2 * 1.86 °C kg/mol * 1 mol/kg = 3.72 °C. Thus, freezing point = 0 - 3.72 = -3.72 °C.