- Acidify the sample with dilute hydrochloric acid and then add a few drops of aqueous barium chloride
- 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
A white precipitate of barium sulfate is a positive result for the presence of sulfate ions
HCl is added first to remove any carbonates which may be present and would also produce a precipitate and interfere with the results.