A Method for a Titration

Add 2 or 3 drops of phenolphthalein indicator to the flask containing potassium hydrogen phthalate. Be sure you have recorded your initial reading of the burette. Place the flask under the burette and titrate the acid by allowing the NaOH solution to flow slowly into the flask. When it appears that the endpoint is near, i.e., the point at which the entire solution just becomes pink, the base should be added so slowly that the color disappears between the addition of each drop and the next. Continue to add base until the pink color barely persists throughout the whole solution for at least 20 seconds. Then record the final burette reading. Repeat the titration with a second sample of potassium hydrogen phthalate. Finally, calculate the molarity of the NaOH solution for each sample. If the agreement isn't within ± 0.01M, do a third sample.