How do you calculate the pH of a solution when given the OH- concentration?
The pH + pOH = 14
The pOH = -log[OH-]
The pH is measure of acidity of a solution whereas the pOH is a measure of basicity of a solution.
The two expressions are opposites expressions. As the pH increases the pOH decreases and vice versa. Both values equal 14.
To convert a concentration of into pH or pOH take the -log of molar concentration of the hydrogen ions or the molar concentration of the hydroxide ion concentration respectively.
pH = -log [ H+]
pOH = -log [OH-]
For example if the [OH-] = 0.01 M, the -log [0.01 ] = 2.0
This is the pOH.
To determine the pH perform the following calculation.
pH = 14.0 - 2.0
pH = 12.0