Question

How much would the freezing point of water decrease if 4 mol of NaCl were added to 1 kg of water (kf=1.86 degrees C/(mol/kg) for water and i=2 for NaCl

A- 7.44 degrees C
B- 14.88
C 3.72
D 1.86

Answer 1

Remember your Collings five properties and use the equation for freezing point depression:

ΔT = i · Kf · m
ΔT = 2 · 1.86 · 4/1
ΔT = 14.88

This means the freezing point will decrease by 14.88C. The answer is B.