This document provides instructions for standardizing a sodium hydroxide solution by titrating it with a primary standard of potassium hydrogen phthalate. It describes cleaning and preparing the buret, titrating the potassium hydrogen phthalate sample, and calculating the molarity of the sodium hydroxide solution based on the titration results. It also discusses using potassium hydrogen phthalate as a primary standard due to its stability and ease of accurate weighing, and explains the titration process and calculating concentration from titration data.