Question

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

Answer 1

`pH=-log_10[H_3O^+]`

Explanation:

And `pOH=-log_10[HO^-]`

We know that under standard condtions, `pH+pOH=14`.

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

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

If `pH=7.5`, then `pOH=14-7.5=6.5`;

by definition, `[H_3O^+]=10^(-7.5)*mol*L^-1`, `[HO^-]=10^(-6.5)*mol*L^-1`. And the solution is slightly basic due to the preponderance of `[HO^-]` ions.

I invite you to complete the remainder of the table.