Answer: - 3.91 °C
Explanation:
1) The depression of the freezing point of a solution is a colligative property and its value is:
ΔTf = m × Kf × i
2) i is the Van't Hoof constant ans for non ionic solutes is 1.
3) m is the molality
m = 2.1 m
3) ΔTf = 2.1 m × 1 × 1.86 °C / mol = 3.91°C.
5) Freezing poin (temperature)
Tf = 0° - 3.91 °C = - 3.91°C
