Define a solution of the primary standard potassium hydrogen phthalate, KHC8H4O4, was prepared by dissolving 0.4877 g of potassium hydrogen phthalate in about 50 mL of water. The Titration with a KOH solution required 26.50 mL to reach a phenolphthalein end point. Explain what is the molarity of the KOH solution?