Search

Which of the following aqueous solutions has the lowest freezing point?


Which of the following aqueous solutions has the lowest freezing point?

(A) 0.2 m NaCl (B) 0.2 m CaCl2

(C) 0.2 m H2SO4

(D) 0.2 m NH3 (E) 0.2 m Al(NO3)3

Answer and Explanation:

Freezing point of a pure solvent depends on the amount of solute that gets dissolved in it. In order to determine which solution has the lowest freezing point, we need to look at the molality as well as whether the solute is ionic or covalent. Since the molality is equal for all of the answer choices, we need to look at what kind of solutes are present.

Choice A: NaCl is ionic since it has a metal and a nonmetal. NaCl dissociates into 2 ions: Na+ and Cl -

Choice B: CaCl2 is ionic since it has a metal and a nonmetal. CaCl2 dissociates into 3 ions: one Ca 2+ and two Cl- ions

Choice C: H2SO4 is a strong acid, and dissociates into 3 ions: two H+ and one SO4 2-

Choice D: NH3 is a covalent compou