freezing point of solution?

Question

Of the following, a 0.1M aqueous solution of _________ will have the lowest freezing point, and why?
A) Al(NO3)3
B) K2CrO4
C) Na2SO4
D) NaCl
E) sucrose

Answer 1

A. Freezing point depression is a function of the number of ions or molecules in solution. This compound provides 4 per mole, while the others provide 3,2 or 1. Note (CrO4)= and SO4= are counted as single ions.