The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g benzene is lowered by 0.45°C. Calculate the degree of dimerization of acetic acid in benzene. Kf for benzene is 5.12 K mol−1 kg, Round off the answer to the nearest integer value. - Sri Chaitanya Infinity Learn Best Online Courses for NCERT Solutions, CBSE, ICSE, JEE, NEET, Olympiad and Class 6 to 12

Solution:

Given $w = 0 .2 g, W = 20 g, ΔT = 0 .45$
${ΔT}_{f} = \frac{1000 (K_{f}) (W)}{M (W)} 0 .45 = \frac{1000 \times 5 .12 \times 0 .2}{20 \times M}$ M(observed) = 113.78
Now for ${CH}_{3} COOH ⇌ {({CH}_{3} COOH)}_{2}$ Before association
0
After association    $1 - α$    $\frac{α}{2}$ Where $α$ is the degree of association
$\frac{M_{nomal}}{M_{observed}} = 1 - α + \frac{α}{2} Or \frac{60}{113 .78} = 1 - α + \frac{α}{2} \Rightarrow α = 0 .945$

The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g benzene is lowered by 0.45°C. Calculate the degree of dimerization of acetic acid in benzene. K_f for benzene is 5.12 $K {mol}^{- 1} kg$ , Round off the answer to the nearest integer value.

Solution:

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