# pOH Concepts Tutorial

## Key Concepts

- pOH is a measure of the hyroxide ion concentration in a solution.
- pOH can be used to describe the basicity (or akalinity) of a dilute aqueous solution at 25°C :
pOH=0 pOH=1 pOH=2 pOH=3 pOH=4 pOH=5 pOH=6 pOH=7 pOH=8 pOH=9 pOH=10 pOH=11 pOH=12 pOH=13 pOH=14 Most Basic ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← ← Least Basic - The lower the value of the pOH of a solution, the more basic (akaline) the solution is.
- pOH can also be used to describe how acidic a solution is:
pOH=0 pOH=1 pOH=2 pOH=3 pOH=4 pOH=5 pOH=6 pOH=7 pOH=8 pOH=9 pOH=10 pOH=11 pOH=12 pOH=13 pOH=14 Least Acidic → → → → → → → → → → → → → → → → → → → → → → → → → → → → Most Acidic The greater the value of the pOH of the solution, the more acidic the solution is.

- For dilute aqueous solutions at 25°C:

A base (alkali) has a pOH less than 7.

An acid has a pOH greater than 7.

If the solution has a pOH of 7 it is said to be neutral, that is, the solution is neither an acid nor a base.pOH=0 pOH=1 pOH=2 pOH=3 pOH=4 pOH=5 pOH=6 pOH=7 pOH=8 pOH=9 pOH=10 pOH=11 pOH=12 pOH=13 pOH=14 Base

pOH < 7neutral

pOH=7Acid

pOH > 7 - Sometimes we might want to describe the relative acidity, or basicity (alkalinity), of a solution.

For this we can use the following terms:pOH=0 pOH=1 pOH=2 pOH=3 pOH=4 pOH=5 pOH=6 pOH=7 pOH=8 pOH=9 pOH=10 pOH=11 pOH=12 pOH=13 pOH=14 Very Basic Basic Slightly Basic neutral

pOH=7Slightly Acidic Acidic Very Acidic Avoid using the terms "strong" or "weak" to describe the relative pOH of acids or bases

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