Question

Calculate the depression in the freezing point of water when 10 g of CH₃CH₂CHClCOOH is added to 250 g of water. K_a = 1.4 × 10⁻³, K_f = 1.86

K kg mol⁻¹.

Answer 1

Molar mass of

∴No. of moles present in 10 g of

It is given that 10 g of is added to 250 g of water.

∴Molality of the solution,

Let α be the degree of dissociation of

undergoes dissociation according to the following equation:

Since α is very small with respect to 1, 1 − α ≈ 1

Now,

Again,

Total moles of equilibrium = 1 − α + α + α

= 1 + α

Hence, the depression in the freezing point of water is given as: