Ahmed is given instructions to carry out the titration labelled ‘1st titration’.
His instructions say:
● Clean a pipette with water and then rinse it with sodium hydroxide solution
● Clean a burette with water and then rinse it with dilute hydrochloric acid
● Use the pipette to transfer 25 cm3 of sodium hydroxide solution into a conical flask
● Add a few drops of acid-base indicator
● Fill the burette with dilute hydrochloric acid and take the reading on the burette
● Add hydrochloric acid from the burette to the alkali in the conical flask, swirling the
contents all the time
● Add the acid drop-by-drop near the end-point until the colour changes
● Take the final burette reading.

Explain why these steps help to ensure that Ahmed’s results are accurate. [6]