Question

The pH of a ${10}^{-8}$ molar solution of HCl in water is:

• A. 8
• B. -8
• C. Between 7 and 8
• D. Between 6 and 7

Answer 1

The correct option is D Between 6 and 7

$\left[H_3{O}^{+}\right]=\left[H_3{O}^{+}\right]from$ $water$ +$\left[H_3{O}^{+}\right]from$ $acid$
$={10}^{-7}+{10}^{-8}$
$=10\times {10}^{-8}+{10}^{-8}=11\times {10}^{-8}$
$pH=log11\times {10}^{-8}=6.95$