In this experiment, we aim to determine the concentration of a solution of sodium hydroxide by titration against a standard solution of potassium hydrogen phthalate. We will use phenolphthalein as an indicator to show when the reaction is complete. To perform the titration, we will need a burette, pipette, conical flask, sodium hydroxide solution, and potassium hydrogen phthalate solution, among other requirements. We will also need to ensure accuracy by recording burette readings to the nearest 0.05 cm3 and repeating titrations until they agree within 0.10 cm3. Finally, we will analyze the effects of various errors on the calculated value of the concentration of sodium hydroxide and discuss the reasons for using a colourless to pink solution for titration.