Question

At $25^{\circ }C$ the $pH$ of a ${\left(10\right)}^{-8}\left(M\right)HCl$ solution in water is

• A. 8
• B. $-8$
• C. between 7 and 8
• D. between 6 and 7

Answer 1

Answer: (D)

$pH$ of ${\left(10\right)}^{-8}\left(M\right)HCl$ will be lesser than 7 as it is acidic solution.
$\left[{\text{H}}^{+}\right]={\left[{\text{H}}^{+}\right]}_{\text{HCl}}+{\left[{\text{H}}^{+}\right]}_{{\text{H}}_{\text{2}}\text{O}}$
$\left[{\text{H}}^{+}\right]=10^{-8}+10^{-7}$
$\therefore \left[{\text{H}}^{\text{+}}\right]=1.1\times 10^{-7}$
$\text{pH}\text{=}\text{6}\text{.96}$