Question

What is the resultant pH of the solution if equal volumes of two solutions with pH=6 and pH=8 are mixed at $25{}^{o}C$?

• A. 7
• B. 6.29
• C. 7.5
• D. 8.29

Answer 1

The correct option is A 7

Let us take the case of 1 litre solution.
$pH=6$
$-log\left[H^{+}\right]=6$
$\left[H^{+}\right]={10}^{-6}$
$pH=8$
$pOH=14-8=6$
$-log\left[O{H}^{-}\right]=6$
$\left[O{H}^{-}\right]={10}^{-6}$

Equal concentraion of $H^{+}$ and $O{H}^{-}$ upon mixing will give a neutral solution $25{}^{o}C$ with pH 7.