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IGCSEChemistryOxford AQARevision NotesChemical AnalysisIdentification of IonsSulfate Ions

Sulfate Ions (Oxford AQA IGCSE Chemistry)

Revision Note

Alexandra Brennan

Written by: Alexandra Brennan

Reviewed by: Stewart Hird

Oxford AQA ChemistryOxford AQA Combined Science Double Award: Chemistry

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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    Author
    Reviewer
    Alexandra Brennan

    Author: Alexandra Brennan

    Expertise: Chemistry

    Alex studied Biochemistry at Newcastle University before embarking upon a career in teaching. With nearly 10 years of teaching experience, Alex has had several roles including Chemistry/Science Teacher, Head of Science and Examiner for AQA and Edexcel. Alex’s passion for creating engaging content that enables students to succeed in exams drove her to pursue a career outside of the classroom at SME.

    Stewart Hird

    Author: Stewart Hird

    Expertise: Chemistry Lead

    Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Topic Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.