Question

If $p{K}_a=4$ and ${\text{K}}_{\text{a}}={\text{Cα}}^{\text{2}}$ , then find van't Hoff factor for a weak HA type acid, when $C=0.01M$ .

• A. $1.01$
• B. $1.02$
• C. $1.10$
• D. $1.20$

Answer 1

Answer: (C)

${\text{K}}_{\text{a}}={\text{Cα}}^2$
$10^{-4}=10^{-2}\times {\text{α}}^2$
$\text{α}=0.1$
$\text{i}=1+\text{α}=1.1$