The document ranks three aqueous solutions by their boiling points from highest to lowest. The solutions are: (I) 0.05 molal urea, (II) 0.03 molal CaCl2, and (III) 0.04 molal AgNO3. It explains that the boiling point is highest for the solution with the greatest i x m product, where i is the van't Hoff factor and m is the molality. Therefore, the correct ranking from highest to lowest boiling point is: (II) 0.03 molal CaCl2, (III) 0.04 molal AgNO3, (I) 0.05 molal urea.

1. Rank the following aqueous solutions in order of decreasing boiling point. I.e. the one with the
highest boiling point should be listed first. Explain reasoning for ranking. (I) 0.05 molal urea
[(NH2)2C=O], (II) 0.03 molal CaCl2, (III) 0.04 molal AgNO3.
a) 0.05 molal urea, 0.03 molal CaCl2, 0.04 molal AgNO3
b) 0.04 molal AgNO3, 0.03 molal CaCl2, 0.05 molal urea
c) 0.03 molal CaCl2, 0.04 molal AgNO3, 0.05 molal urea
d) 0.05 molal urea, 0.04 molal AgNO3, 0.03 molal CaCl2
e) 0.03 molal CaCl2, 0.05 molal urea, 0.04 molal AgNO3
f) 0.04 molal AgNO3, 0.05 molal urea, 0.03 molal CaCl2
g) none of the above
Solution
(I) 0.05 molal urea [(NH2)2C=O],
molality = 0.05 m
concentration = 0.05 x 1 = 0.05 m
(II) 0.03 molal CaCl2,
i = 3
concentration of CaCl2 = 3 x 0.03 = 0.09 m
(III) 0.04 molal AgNO3.
i = 2

2. concentration of AgNO3 = 2 x 0.04 = 0.08 m
delta Tb = i x Kb x m
i x m product is more , then boiling point also more.
highest boiling point : 0.03 molal CaCl2
ranking :
c) 0.03 molal CaCl2, 0.04 molal AgNO3, 0.05 molal urea