| Lesson Plan |
| Grade: Year 10 |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Describe tests to identify the anions: (a) carbonate, $\mathrm{CO}_3{ }^{2-}$, by reaction with dilute acid and then testing for carbon dioxide gas (b) chloride, $\mathrm{Cl}^{-}$, bromide, $\mathrm{Br}^{-}$, and iodide, $\mathrm{I}^{-}$, by acidifying w |
Learning Objective/s:
- Describe qualitative tests for carbonate, halide, nitrate, sulfate and sulfite ions.
- Explain the chemical reactions and observations that confirm each ion.
- Apply the tests to identify unknown ionic samples safely.
- Interpret gas‑evolution tests using limewater and litmus indicators.
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Materials Needed:
- Dilute HCl and H2SO4
- Dilute HNO3
- Silver nitrate solution
- Barium nitrate solution
- Concentrated NaOH
- Aluminium foil pieces
- Potassium permanganate solution
- Test tubes, delivery tubes, limewater (Ca(OH)2)
- Litmus paper, dilute ammonia solution
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Introduction:
Begin with a quick question: “How do chemists recognise invisible gases in the lab?” Students recall that precipitation and gas‑evolution reactions are key. Review the concept of acid‑base reactions and solubility rules. State that by the end of the lesson they will be able to correctly perform and interpret five common anion tests.
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Lesson Structure:
- Do‑now (5′): Students list from memory the reagents used for carbonate, halide, nitrate, sulfate and sulfite tests.
- Teacher demonstration – carbonate test (10′): Add dilute acid to a sample, observe effervescence, pass gas into limewater and note the milky precipitate.
- Guided practice – halide identification (15′): In groups add AgNO3 to acidified samples, record precipitate colour, then add dilute NH3 to confirm each halide.
- Brief demo – nitrate test (5′): Heat sample with aluminium foil and conc. NaOH, smell NH3 and test with red litmus.
- Group activity – sulfate & sulfite tests (10′): Add Ba(NO3)2 for sulfate, add acidic KMnO4 for sulfite, observe precipitates and gas reactions.
- Check for understanding (5′): Exit‑ticket matching each ion to its key observation.
- Summary & reflection (5′): Teacher recaps the five tests, emphasising the logic behind each observation.
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Conclusion:
Review the main steps and why each reagent is specific to its ion. Students complete an exit ticket that asks them to choose the correct test for a given observation. For homework, they finish a worksheet that includes unknown sample scenarios requiring selection of the appropriate qualitative test.
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