Paper 2 - Acids, bases and salt preparations

Question 1

Describe how to carry out an acid-alkali titration

Answer 1

• Using a pipette and a pipette-filler, add 25cm^3 of alkali to a conical flask with 2 or 3 drops of an indicator such as phenolpthalein
• Fill a burette with the acid and do this below eye level to prevent damage to the eyes if acid spills
• Using the burette, add the acid to the alkali slowly, regularly swirl the conical flask to ensure the acid and alkali are mixing
• Add acid very slowly when you are near the endpoint and the colour change is about to occur (Phenolphthalein will turn from pink to colourless)
• The indicator will change colour when all the alkali has been neutralised
• Record the volume of acid used to neutralise the alkali
• Repeat 5 times and take an average