Answer : The value of Ka for acetic acid is, [tex]2.03\times 10^{-5}[/tex]
Explanation :
The chemical formula of acetic acid is, [tex]CH_3COOH[/tex].
The chemical equilibrium reaction will be:
[tex]CH_3COOH\rightleftharpoons CH_3COO^-+H^+[/tex]
Given:
pH = 2.96
First we have to calculate the concentration of hydrogen ion.
[tex]pH=-\log [H^+][/tex]
[tex]2.96=-\log [H^+][/tex]
[tex][H^+]=1.096\times 10^{-3}M[/tex]
That means,
[tex][H^+]=[CH_3COO^-]=1.096\times 10^{-3}M[/tex]
[tex][CH_3COOH]=0.0602-(1.096\times 10^{-3})=0.0591M[/tex]
The expression for reaction is:
[tex]K_a=\frac{[CH_3COO^-][H^+]}{[CH_3COOH]}[/tex]
[tex]K_a=\frac{(1.096\times 10^{-3})\times (1.096\times 10^{-3})}{0.0591}[/tex]
[tex]K_a=2.03\times 10^{-5}[/tex]
Thus, the value of Ka for acetic acid is, [tex]2.03\times 10^{-5}[/tex]
