First slide

Ionization constants of weak acids, PH of weak acids

Question

For a weak acid, the concentration of H⁺ ions is given by

Easy

A

$\large \sqrt {{K_a}.C}$
B

$\frac{{{K_a}}}{C}$
C

$\sqrt {\frac{{{K_a}}}{C}}$
D

$\sqrt {\frac{C}{{{K_a}}}}$

Solution

$C{H_3}COOH$ $\rightleftharpoons$ ${H^ + }$ $+$ $C{H_3}CO{O^ - }$

t=0 C₀ 0 0

t=t_eq C₀-C₀α C₀α C₀α

${K_a} = \frac{{\left ({C_0}\alpha \right ) \left ({C_0}\alpha \right )}}{{{C_0} - {C_0}\alpha }}$ $= \frac{{{C_0}{\alpha ^2}}}{{1 - \alpha }}$ $\rightarrow$ (1)
For a weak acid, 1 - α ~ 1
${C_0}\left( {{K_a}} \right) = {C_0}{\alpha ^2} \times {C_0}$
${C_0}\left( {{K_a}} \right) = {\left( {{C_0}\alpha } \right)^2}=[H^+]^2$
$[H^+]=\sqrt{K_aC_0}$

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