Question

g Which of the following solutes in aqueous solution would be expected to exhibit the smallest freezing-point lowering (assuming ideal behavior)? In other words, which one would have the highest freezing point temperature? A) 0.20 m CaCl2 B) 0.50 m C2H5OH (ethanol) C) 0.10 m Al(NO3)3 D) 0.25 m NH4Br E) 0.30 m NaCl

Answer 1

Answer:

0.10 m Al(NO3)3

Explanation:

Let us note that the substance that has the highest freezing point will have the lowest freezing point depression. Since;

ΔTf = Kf m i

ΔTf  = freezing point depression

Kf = freezing point constant

m = molality

i = Van't Hoft factor

Given that the freezing point depression depends on the molality and the Van't Hoft factor (number of particles), we can see that 0.10 m Al(NO3)3 has the least freezing point depression and highest freezing point temperature because it gives the least value of m * i. That is 0.10 m * 4 = 0.4