pOH:

It  is  also  significant  to  understand  the  relationship  among  the  [H⁺]  and  the  [O- H ] concentrations.  A pOH of a solution is described as the negative logarithm of the hydroxyl concentration that represented as [OH-] in moles/liter.

pOH   = -log [OH^-]

[OH^-]  = 10^-pOH

For  water  solutions,  a  product  of  the  hydrogen  ion  concentration  and  the  hydroxyl concentration is always 1 x 10-14 at 25ºC.  This means in which the sum of pH and pOH is equivalent to 14 under these conditions.

[H⁺] x [OH-]   = 1 x 10^-14

pH + pOH     = 14