. The freezing point depression constant for water is 1.86 ° Cm^-1


The freezing point depression constant for water is 1.86 ° Cm-1. If 5 g is dissolved in 45 g H2O, the freezing point is changed by - 3.82 °. Calculate the van't Hoff factor for Na2SO4

A: 0.381

B: 2.05

C: 2.63

D: 3.11

Best Answer

Explanation:

For depression in freezing point the formula is

T=Kfm

m = molality

molality(m) = number of moles/mass of solvent in Kg

m = 5x1000/ Mx 45

3.82 = 1.86x5x1000/ Mcal x45
Mcal= 54.10g

vant hoff"s factor (i) = Mobs/Mcal

i = 142/54.1 = 2.624 ≈ 2.63

Final Answe:

The van’t hoff factor (C) (i) = 2.63

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