Question

Rank the following from lowest to highest freezing point (using the vant hoff factor) HNO3-, Ba(NO3)2, sucrose, and NH3(which is a weak Electrolyte according to my textbook). ALL OF THEM HAVE A .01m

Answer 1

ΔT = iKfm

where
ΔT = Change in temperature in °C (decreasing temperature)
i = van 't Hoff factor
Kf = molal freezing point depression constant or cryoscopic constant in °C kg/mol
m = molality of the solution

Kf and molality of the given solutions are same. Only i value differs.

Greater i value greater decreasing temperature

i value = number of independent ions are produced in solution.

HNO3 = H+ and NO3^- , 2 ions

Ba(NO3)2 = Ba2+ and 2 NO3^- , 3 ions

Sucrose = non ionic, 0 ions

NH3 = weak electrolyte (partial ionic), fractions of ions

So answer

Sucrose < NH3 < HNO3 < Ba(NO3)2