Question

In a solvent 50% of an acid HA dimerizes and the rest dissociates. The van't Hoff factor of the acid is $x\times {10}^{-2}$. The value of x(Round off to the Nearest Integer) is

• A. 125.0
• B. 125
• C. 125.00

Answer 1

Answer: (A), (B), (C)

$i=\frac{\text{Total number of particle after dissociation/association}}{\text{Total number of particle before dissociation/association}}$

let 'a' are total moles of $HA$

$\underset{0.5a}{HA}⟶\underset{0.5a}{H^{+}}+\underset{0.5a}{A^{-}}$

$\underset{0.5a}{HA}⟶\underset{\frac{0.5a}{2}}{(HA{)}_2}$

$i=\frac{(0.5+0.5+\frac{0.5}{2})a}{a}=1.25=125\times {10}^{-2}$