20% of Acetic acid is dissociated when its 5 g is added to 500 ml of water. The depression in the freezing point of such water is_______ x 10^-3°C. Atomic mass of C, H and O are 12,1 and 16 a.m.u. respectively.
[Given : Molal depression constant and density of water are 1.86 K kg mol^-1 and 1 g cm^-3 respectively]

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away

An Intiative by Sri Chaitanya

answer is 372.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

Molality of given acetic acid solution is
$\begin{array}{l} = \frac{5 g}{60 g \cdot {mol}^{- 1}} \times \frac{1}{0.5 kg} \\ = \frac{1}{6} mol {kg}^{- 1} \end{array}$
Degree of dissociation = 0.2
Van’t Hoff factor $(i) = 1.2$
Depression in freezing point $({ΔT}_{f})$
$\begin{array}{l} = K_{f} . i . m \\ = (1.86) (1.2) (\frac{1}{6}) \\ = 0.372 K or 0 . 372^{\circ} C \\ = 372 \times {10^{- 3}}^{\circ} C \end{array}$