Question

A solution of a base that has a pH of $9.0$ has a hydrogen ion concentration of:

• A. $1\times {10}^9$ molar
• B. $1\times {10}^5$ molar
• C. $1\times {10}^{-5}$ molar
• D. $1\times {10}^{-7}$ molar
• E. $1\times {10}^{-9}$ molar

Answer 1

The correct option is E $1\times {10}^{-9}$ molar

GIven, $pH=9.0$

We have, $pH+pOH=14$

$\therefore pOH=5$

Now, $pOH=-lo{g}_{10}\left[O{H}^{-}\right]$

$\therefore \left[O{H}^{-}\right]={10}^{-5}$

As we know, $\left[H^{+}\right]\left[O{H}^{-}\right]={10}^{-14}$

$\therefore \left[H^{+}\right]={10}^{-9}$