Which of the following liquids will have the lowest freezing point?

A. aqueous LiF (0.65 m)
B. Pure #H_2O#
C. aqueous sucrose (0.75 m)
D. aqueous #CdI_2# (0.39 m)
E: aqueous glucose (0.75 m)

Thanks in advance

1 Answer

It should be D as the true answer, but if we ignore the impossible concentration of LiF, the intended answer is probably A.


According to colligative properties of solutes, depression of freezing point follows the number of particles produced upon solubilization. It depends on the concentration of #CdI_2 #, which is 0.39 molal.

Theoretically #CdI_2# giving three ions per formula when dissolved in water, should give the second highest freezing depression, at that concentration.

On the other hand #LiF# is actually sparingly soluble in water (about 0.071 M), and cannot be dissolved at 0.65 molal.

So the answer depends on whether we want to represent physical reality or answer a theoretical question. [Sucrose and glucose give only one particle per molecule.]