- We have learned that, all salts of sulphate are soluble in water, except lead(II) sulphate, barium sulphate and calcium sulphate.
- The insolubility of barium sulphate is used to test for the presence of sulphate in a salt.
- 2 cm3 of dilute hydrochloric / nitric acid is added to 2 cm3 of sulphate solution. This is to check whether carbonate is presence in the solution or not because carbonate may give the same result as sulphate.
- If not effervescence, then 2 cm3 of barium chloride is added into the solution.
- If sulphate ions are presence, a white precipitate will form. The precipitate is barium sulphate.
- This is actually the double decomposition reaction that you have learned in preparation of insoluble salt.
Ba2+ + SO42– → BaSO4