pH is a measure of how acidic or how basic a liquid solution. It converts the concentration of hydrogen ions in a solution to a number between 1 and 14.
pH is given with the equation:
$$ pH = -log_{10}[H^+] $$
For example:
If the concentration of hydrogen ions is $1 \times 10^{-7}$ gram-equivalents per litre:
$$ pH = -log_{10}(1 \times10^{-7})\\ pH = -(-7)\\ pH = 7 $$
This means that a substance that has a hydrogen concentration of $1 \times 10^{-7}$ gram-equivalents per litre, is neutral.
pOH can be used as an indicator of a solutions’ alkalinity or even electrical conductivity. It converts the concentration of hydroxide ions in a solution to a number between 1 - 14 [citation needed].
It is given by the equation:
$$ pOH = -log_{10}[OH^-] $$
For example, if the concentration of $OH^-$ ions is $1 \times 10^{-12}$
$$ pOH = -log_{10}(1 \times 10^{-12})\\ pOH = -log_{10}(10^{-12})\\ pOH = 12 $$
pOH and pH are related using the $K_w$(self-ionization constent of water).
$$ OH^- = \frac{K_w}{H^+}\\ pOH = 14-pH\ \{\text{taking logorithm of both sides}\}\\ pOH + pH = 14 $$