Question

Benzoic acid undergoes dimerization in benzene solution.
Then, the van't Hoff factor $\left(i\right)$ is related to the degree of association of the acid $\left(\alpha \right)$ as :

• A. $i=(1+\alpha )$
• B. $i=(1-\alpha )$
• C. $i=(1-\frac{\alpha }{2})$
• D. $i=(1+\frac{\alpha }{2})$

Answer 1

The correct option is C $i=(1-\frac{\alpha }{2})$

$2C_6{H}_{5}COOH\to {\left(C_6{H}_{5}COOH\right)}_2$
$\text{Initially:}C0$$\text{Finally:}C-C\alpha \frac{C\alpha }{2}$
$i=\frac{\text{No. of moles after dissociation}}{\text{No. of moles before dissociation}}$

$i=\frac{\frac{C\alpha }{2}+C-C\alpha }{C}$
$i=1-\frac{\alpha }{2}$