Question

1.2 mL of acetic acid is dissolved in water to make 2.0 L of solution. The depression in freezing point observed for this strength of acid is 0.0198°C. The percentage of dissociation of the acid is ____ . (Nearest integer) 
[Given: Density of acetic acid is 1.02 g mL^–1.. 
Molar mass of acetic acid is 60 g mol^–1 
K_f(H₂O) = 1.85 K kg mol^–1].

Answer 1

Correct Answer: 5

The correct answer is: 5

ΔT_b = i × K_b × m

\(=\frac{1.2×1.02}{60}\)

As moles of solute are very less.

So, take molarity and molality same.

\(0.0198=i×1.85×1.2×\frac{1.02}{60×2}\)

\(i = 1.05\)

\(α=\frac{i-1}{n-1}=\frac{0.05}{1}=0.05\)