# If pH=7.5, what is pOH, and what is [HO^(-)]?

Nov 23, 2016

$p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right]$

#### Explanation:

And $p O H = - {\log}_{10} \left[H {O}^{-}\right]$

We know that under standard condtions, $p H + p O H = 14$.

And where $p H < 7$, an acidic solution is specfied; $p H > 7$, an basic solution is described. What sort of solution do we have at $p H = 7$?

Given a calculator, those bits of information are all we need to solve these problems:

If $p H = 7.5$, then $p O H = 14 - 7.5 = 6.5$;

by definition, $\left[{H}_{3} {O}^{+}\right] = {10}^{- 7.5} \cdot m o l \cdot {L}^{-} 1$, $\left[H {O}^{-}\right] = {10}^{- 6.5} \cdot m o l \cdot {L}^{-} 1$. And the solution is slightly basic due to the preponderance of $\left[H {O}^{-}\right]$ ions.

I invite you to complete the remainder of the table.