Identifying non-metal ions (T)

• What types of non-metal ions can be identified?

  Carbonate, halides, and sulfate
• What is the first step in testing for carbonate ions?

  Add dilute acid to the sample
• What gas is produced when carbonate reacts with acid?

  Carbon dioxide gas
• What indicates the presence of carbon dioxide gas during the carbonate test?

  Effervescence or fizzing
• How do we confirm the presence of carbon dioxide gas?

  Bubble the gas through lime water
• What happens to lime water if carbon dioxide is present?

  It goes cloudy
• What is the first step in testing for halide ions?

  Add dilute nitric acid to the sample
• What is added after dilute nitric acid in the halide test?

  Add dilute silver nitrate solution
• What color precipitate do chloride ions produce?

  White precipitate of silver chloride
• What color precipitate do bromide ions produce?

  Cream precipitate of silver bromide
• What color precipitate do iodide ions produce?

  Yellow precipitate of silver iodide
• What is the first step in testing for sulfate ions?

  Add dilute hydrochloric acid to the sample
• What is added after hydrochloric acid in the sulfate test?

  Add barium chloride solution
• What indicates the presence of sulfate ions?

  A white precipitate forms
• What are the stages for testing carbonate ions?

  1. Add dilute acid to the sample.
  2. Observe effervescence (fizzing).
  3. Bubble gas through lime water.
  4. If lime water goes cloudy, carbonate is present.
• What are the stages for testing halide ions?

  1. Add dilute nitric acid to the sample.
  2. Add dilute silver nitrate solution.
  3. Observe precipitate color:

  • White for chloride
  • Cream for bromide
  • Yellow for iodide
• What are the stages for testing sulfate ions?

  1. Add dilute hydrochloric acid to the sample.
  2. Add barium chloride solution.
  3. Observe white precipitate for sulfate presence.