Question

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

Answer 1

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

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

A `"1.05 M"` `"NaOH"` solution has `"1.05 M"` of dissociated `"OH"^(-)` anions, since dissociating `"NaOH"` generates an equimolar quantity of `"OH"^(-)`:

`"NaOH"(s) stackrel("H"_2"O"(l)" ")(->) "Na"^(+)(aq) + "OH"^(-)(aq)`

So, the `"pOH"` is

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

`= -0.0212`

Now recall that `"pH" + "pOH" = 14`.

Hence, `color(blue)("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."