Cambridge IGCSE Chemistry · Syllabus 0620 · Acids, Bases and Salts
Titration
What is Titration?
A method of preparing a soluble salt from an acid and an alkali in which the exact volume of acid needed to react with a measured volume of alkali is found using an indicator, and the preparation is then repeated with the same volumes and no indicator so that the crystals are not contaminated.
This definition is part of the Acids, Bases and Salts chapter in Cambridge IGCSE Chemistry.
Common mistakes with Titration
- “Mix the acid and the alkali, then filter off the salt.” Repair There is nothing solid to filter. Both reactants are dissolved and so is the salt. That is precisely why an acid–alkali preparation must be done by titration — you have to measure the right volume, because you cannot remove an excess afterwards.
- “Titrate to the end point, then evaporate that flask to get the crystals.” Repair That flask contains indicator, which would be trapped in the crystals and colour the product. Record the volume from the titration, then repeat with the same measured volumes and no indicator, and crystallise that solution.
Examiner tips on Titration
- The two sentences that carry the whole method “An excess of an alkali cannot be removed by filtration, because it is dissolved — so the volumes must be measured instead.” and “The titration is repeated without indicator so that the indicator does not contaminate the crystals.” Those two ideas are what separate a described method from a memorised one: each names the property of the reagents that forces the step.