Question

A dilute solution Contains “x” moles of solute “A” in 1 kg of solvent with molal elevation constant kb. The solute dimerises in the solution according to the following equation. The degree of association is $\left(\alpha \right)$
$2A\rightleftharpoons A_2$

The von’t Hoff factor will be

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

Answer 1

The correct option is B

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

A dilute solution Contains “x” moles of solute “A” in 1 kg of solvent with molal elevation constant kb. The solute dimerises in the solution according to the following equation. The degree of association is $\left(\alpha \right)$
$2A\rightleftharpoons A_2$

For association $i=1+\propto (\frac{1}{n}-1)$