Question

Compute the $pH$ of a solution at ${25}^{o}C$ which is twice as alkaline as pure water.

• A. 6.7
• B. 6.4
• C. 7.3
• D. 7.6

Answer 1

The correct option is C 7.3

In pure water,

$\left[{OH}^{-}\right]=\left[H^{+}\right]={10}^{-7}M$ at ${25}^{0}c$

Given $\left[{OH}^{-}\right]=2\times {10}^{-7}M$.

So, $pOH=-log(2\times {10}^{-7})$

$=6.69$

$\therefore$ $pH=14-6.69=7.31$