# Is it okay to have a "pH" above 14?? Apparently "1.05 M" "NaOH" has a "pH" above 14 at 25^@ "C".

Jun 7, 2016

A $\text{pH}$ above $14$ is totally fine. Despite what you may learn about a [common] $\text{pH}$ range of $0 - 14$, it doesn't mean $\text{pH}$ can't be negative, or above $14$.

Let's go through it again, just to see what I get in comparison.

A $\text{1.05 M}$ $\text{NaOH}$ solution has $\text{1.05 M}$ of dissociated ${\text{OH}}^{-}$ anions, since dissociating $\text{NaOH}$ generates an equimolar quantity of ${\text{OH}}^{-}$:

${\text{NaOH"(s) stackrel("H"_2"O"(l)" ")(->) "Na"^(+)(aq) + "OH}}^{-} \left(a q\right)$

So, the $\text{pOH}$ is

"pOH" = -log["OH"^(-)]

$= - 0.0212$

Now recall that $\text{pH" + "pOH} = 14$.

Hence, $\textcolor{b l u e}{\text{pH" = 14 - "pOH} = 14.02 > 14.0}$.

If you still are wondering, "really? It's true?", then perhaps reading this note from this website can reassure you:

"The pH scale does not have an upper nor lower bound."