An aqueous solution of potassium sulfate (k2so4) has a freezing point of -2.24
c. what is its molality? (kf=1.86
c.

An aqueous solution of potassium sulfate exhibits colligative properties. Colligative properties are properties that depends on the concentration of a substance in a solution. These properties are freezing point depression, vapor pressure lowering, osmotic pressure and boiling point elevation. For this problem we use the concept of freezing point depression since we are given the freezing point of the solution. Freezing point depression is as:
 
ΔT = -k(f) x m x i
-2.24 - 0 = -1.86 x m x 3
m = 0.4014

Thus, the molality of the solution is 0.4014.