Question

How do you determine when enough NaOH solution has been added to just neutralize the KHC8H4O4?

Answer 1

KHC₈H₄O₄ (commonly known as potassium hydrogen phthalate or KHP) is a weak acid which dissociates in aqueous solution to give hydronium ions, potassium ions and phthalate ions.

Using a suitable indicator like phenolphthalein, we can determine the amount of NaOH required to neutralize KHP

Phenolphthalein is a color based indicator which is colorless when present in acid solution but has a pink color in basic solution

When a solution of KHP (with 2-3 drops of phenolphthalein indicator in it) is titrated with NaOH, the color of solution changes to light pink when enough NaOH has been added to just neutralize all KHP

Hence by the color of solution at end-point, we can determine the amount of NaOH