Titrations

Acid-alkali titrations

• The concentration of an acid or alkali can be calculated by carrying out an experiment called a titration.
• Materials
  • The apparatus needed includes:
  • a pipette to accurately measure a certain volume of acid or alkali
  • a pipette filler to use the pipette safely
  • a conical flask to contain the liquid from the pipette
  • A burette

Apparatus needed to carry out a titration

Method

• This is an outline method for carrying out a titration in which an acid is added to alkali.

1. Use the pipette and pipette filler to add 25 cm3 of alkali to a clean conical flask.
2. Add a few drops of indicator and put the conical flask on a white tile.
3. Fill the burette with acid and note the starting volume.
4. Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
5. Stop adding the acid when the end-point is reached (the appropriate colour change in the indicator happens). Note the final volume reading.

• The same method works for adding an alkali to an acid – just swap around the liquids that go into the conical flask and burette.