Testing Water Purity

Water companies test water regularly to ensure pollutant levels do not exceed limits. Can test for dissolved ions using precipitation reactions.

1. Test for sulphate ions using barium chloride:

• Add dilute hydrochloric acid to test sample.
• Add 10 drops of barium chloride solution.
• If white precipitate, there are sulphate ions in sample.
• Barium ions + sulphate ions --> barium sulphate
• Ba2+ + SO42- --> BaSO4

Barium chloride + postassium…