Question

The pH of a ${10}^{-8}$ M HCl solution is approximately:

• A. $8.0$
• B. $6.96$
• C. $7.0$
• D. $14.0$

Answer 1

The correct option is B $6.96$

We have a ${10}^{-8}MHCl$ solution.

Therefore, the $H^{+}$ concentration from acid $={10}^{-8}$

The $H^{+}$ concentration from water (neutral) $={10}^{-7}$

Total concentration of $H^{+}={10}^{-8}+{10}^{-7}$

Therefore, the value of $pH=-log({10}^{-8}+{10}^{-7})=6.96$

Hence, the pH of a ${10}^{-8}MHCl$ solution is approximately $6.96$.

Option B is correct.