Question

$pH$ of ${10}^{-8}$ N $NaOH$ solution is:

• A. 7.2
• B. 6.8
• C. 6.98
• D. 7.02

Answer 1

The correct option is D 7.02

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

$K_w$ = ${\left[H\right]}^{+}{\left[OH\right]}^{-}$ = $1\times {10}^{-14}$

${\left[OH\right]}^{-}$ = $1\times {10}^{-7}$ M

The Total Concentration = $1\times {10}^{-7}+1\times {10}^{-8}$ = $1.1\times {10}^{-7}M$

$pH=-log\left[1.1\times {10}^{-7}\right]$ = 6.98

$pOH=7.02$