Sulfate Ions (Oxford AQA IGCSE Combined Science Double Award)

Revision Note

Test for Sulfate Ions

  • Acidify the sample with dilute hydrochloric acid and then add a few drops of barium chloride solution

  • If a sulfate is present then a white precipitate of barium sulfate is formed:

Ba2+ (aq) + SO42- (aq) → BaSO4 (s)

  • The test can also be carried out with barium nitrate solution

Testing for sulfate ions 

The diagram shows barium chloride solution being added to a sample, which forms a white precipitate if sulfate ions are present
A white precipitate of barium sulfate is a positive result for the presence of sulfate ions

Examiner Tips and Tricks

HCl is added first to remove any carbonates which may be present which would also produce a precipitate and interfere with the results.

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