Change in freezing point = Kf * (molality)* i
1) Kf for acetic acid = 3.90 C/molal
2) Molality = moles solute/kilograms
3.00 grams Mg(ClO2)2/ 30.0 g acetic acid x 1000 g/kg x 1mole Mg(ClO2)2 /159.2 grams = 0.628
3) i is the van’t hoff factor ;
Mg(ClO2)2 ; 24.3 + 2(35.45) + 4(16) = 159.2
Mg(ClO2)2 ==⇒ Mg2+ + 2ClO2-
The value of i is 3, since 3 ions are produced
Change in freezing point = 3.90 C/molal x 0.628 x 3 = 7.35 Celsius
Freezing point of solution = 16.6 – 7.35 = 9.3 Celsius
