The reaction between KHP and NaOH is shown by the balanced equation KHC8H4O4 + NaOH = NaKC8H4O4 + H2O. KHP stands for potassium hydrogen phthalate, which has the chemical formula KHC8H4O4.
When KHP and NaOH combine, a positive hydrogen ion leaves the KHC8H4O4 and a negative hydrogen atom leaves the NaOH. These two atoms combine with the oxygen from the NaOH to form H2O, which is the chemical formula for water. The reaction between the two solutions is typically done using a process called titration, so that the concentration and volume of each solution is known both before and after the reaction. The reaction may also be called standard titration or just standardization.