Question: 63: 0.01 M acetic acid solution is 1 \% ionised, then pH of this acetic acid solution is :
(1) 3
(2) 2
(3) 4
(4) 1
Answer: Option (3)
Explanation:
Acetic acid is a weak acid and is partially ionised in aqueous solution.
Given concentration of acetic acid is 0.01\,\text{M}
and percentage ionisation is 1\%.
Fraction ionised is:
\frac{1}{100} = 0.01Hydrogen ion concentration produced is:
[\mathrm{H}^+] = 0.01 \times 0.01 = 1 \times 10^{-4}\,\text{M}pH of the solution is given by:
\mathrm{pH} = -\log [\mathrm{H}^+]Substituting the value:
\mathrm{pH} = -\log(1 \times 10^{-4}) = 4Therefore, the pH of the acetic acid solution is 4.
Hence, option (3) is correct.