Question

What is the pOH if the pH is 11.25?

Answer 1

`2.75`

Explanation:

The relationship between `"pH"` and `"pOH"` is that they always add up to `14`. Therefore, `"pOH"=14-"pH"`, so `"pOH"=14-11.25=2.75`

Answer 2

2.75

Explanation:

The general rule is that the pH and pOH of a solution have to add up to 14. The reason for this has to do with the equilibrium constant of water amongst other things, and for the sake of time and brevity I shall not go into that.

So, given that pH and pOH add up to 14, the problem is just simple algebra:

`pH + pOH = 14`
`pOH = 14 - pH`
`pOH = 14 - 11.25 = 2.75`

This indicates a particularly strong concentration of hydroxide ions, because the "p" scale means negative logarithm of. As a result, a smaller pOH means a larger concentration of hydroxide ions.

For a better understanding of what pH and pOH are, I'd recommend checking out this video.

Hope that helped :)