First slide

Acidic buffer

Question

An acidic buffer contains

Easy

A

Excess of H⁺ ions, few anions and excess of undissociated molecules of weak acid
B

Excess of cations, few OH^- ions and some undissociated molecules of weak acid.
C

Excess of anions, few H⁺ ions and some undissociated molecules of weak acid
D

Strong acid and its salt with a weak base

Solution

$\mathop {C{H_3}COOH}\limits_{a - x} \,\,\,\,\,\, \rightleftharpoons \,\,\,\,\mathop {C{H_3}CO{O^ - }}\limits_{x + s} + \mathop {{H^ + }}\limits_x$

$\mathop {C{H_3}COONa}\limits_{s - s} \,\,\,\,\,\, \rightleftharpoons \,\,\,\,\mathop {C{H_3}CO{O^ - }}\limits_{s + x} + \mathop {{H^ + }}\limits_s$

${K_a} = \frac{{\left (x + s \right ) + \left[ {{H^ + }} \right]}}{{\left (a - x \right )}} \Rightarrow \left[ {{H^ + }} \right] = {K_a}\frac{{\left( {acid} \right)}}{{\left (salt \right )}};\mathop {neglecting}\limits_x$ .

${K_a} = \frac{{\left (x + s \right ) + \left[ {{H^ + }} \right]}}{{\left (a - x \right )}} \Rightarrow {P^H} = {P^{{K_a}}} + \log \frac{{\left[ {salt} \right]}}{{\left[ {acid} \right]}}$

Due to common ion effect the dissociaiton of the acetic acid is very less. the amount of H⁺ ions will be less.

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App