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
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
The water from the lake must first evaporate from the liquid state to the gaseous state and then condense in the air to form vapors. The water molecules absorb energy while evaporating and release it when condensing. Their motion gets faster when they are evaporating and slows back down upon condensation.
