Question

The pH value of ${10}^{-3}M$ aqueous solution of $NaCl$ is:

• A. $7$
• B. $3$
• C. $11$
• D. $14$

Answer 1

The correct option is A $7$

$NaCl$ is a salt of strong acid and strong base so it hydrolyses completely.

$NaCl+H_{2}O\to NaOH+HCl$

$N{a}^{+}+C{l}^{-}+H_{2}O\to N{a}^{+}+O{H}^{-}+H^{+}+C{l}^{-}$

$H_{2}O\to H^{+}+O{H}^{-}$

$K_h=\left[H^{+}\right]\left[O{H}^{-}\right]=K_w={10}^{-14}$

So $pH=-\log \left[H^{+}\right]=7$