Question

The freezing point depression constant for water is 1.86° k kg mol^-1. If 5g Na₂SO₄ is dissolved in 45g water, the depression in freezing point is 3.64°C. The van’t Hoff factor for Na₂SO₄ is …….. 

(a) 2.50 

(b) 2.63 

(c) 3.64 

(d) 5.50

Answer 1

(a) 2.50 

K_f = 1.86 

W₂ = 5g 

∆T_f = 3.64 

M₂ = 142 

W₁ = 45g

ΔT_f = i x K_f

i = 2.5