Name: pH Scale
Uploaded: 2019-07-19
Duration: 9 min 45 s
Description: This video discusses the pH of acids, bases, and salts and also the limitations of using a pH scale for identification. The natural indicators do the verific...

Question

What are strong and weak electrolytes? Derive an expression for the calculation of the degree of ionization of a weak electrolyte.

Accepted Answer

Strong electrolytes: Those ionic conductors which are completely ionized in aqueous solution.
E.g. $NaCl$ , $KCl$ etc.

Weak electrolytes: Those electrolytes which are partially ionized in aqueous solution.
E.g. $HCN$ , ${CH}_{3} COOH$ etc.

Degree of ionization of a weak electrolyte:
${CH}_{3} COOH + H_{2} O ⇌ {CH}_{3} {COO}^{-} + H_{3} O^{+} Initial conc . C Conc . at Eq . C - Cα Cα Cα$

The change in concentration of water is not much therefore it is taken constant.

Here, $C$ is the initial concentration and $α$ is the degree of dissociation/ionization.

$∴ K_{a} = \frac{(Cα) (Cα)}{C (1 - α)}$
For a weak electrolyte, $α ≪ 1$
$∴ 1 - α \approx 1$

$\Rightarrow K_{a} = {Cα}^{2} \Rightarrow α = \sqrt{\frac{K_{a}}{C}}$
$K_{a}$ is dissociation constant or ionization constant for an acid.

What are strong and weak electrolytes? Derive an expression for the calculation of the degree of ionization of a weak electrolyte.

Important Questions on Ionic Equilibrium in Solution

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