1. Tardigrade
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  3. Chemistry
  4. The freezing point of benzene decreases by 0.45°C when 0.2 g of acetic acid is added to 20 g of benzene. If acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be: (Kf for benzene = 5.12 K kg mol-1)

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Q. The freezing point of benzene decreases by $0.45^{\circ}C$ when $0.2\, g$ of acetic acid is added to $20\, g$ of benzene. If acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be :
($K_f$ for benzene = $5.12 \, K \, kg \, mol^{-1}$)

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Solution:

$0.45 = i (5.12) \frac{0.2 / 60}{20} \times 1000$

$\Rightarrow i =0.527$

$\underset{1-\alpha}{2 CH _{3} COOH } \rightleftharpoons \underset{\frac{\alpha}{2}}{(CH _{3} COOH)_{2}}$

$\Rightarrow i =1-\frac{\alpha}{2}$

$\Rightarrow 0.527=1-\frac{\alpha}{2}$

$\Rightarrow \frac{\alpha}{2}=0.473$

$\Rightarrow \alpha=0.946$

$\therefore \%$ association $=94.6 \%$