Testing for anions sim
Each tube holds 2.0 cm³ of a 0.1 mol/dm³ solution of one sodium salt; the eighth holds 5 cm³ of limewater.
Testing for anions · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Each tube holds 2.0 cm³ of a 0.1 mol/dm³ solution of one sodium salt; the eighth holds 5 cm³ of limewater. Acidify with 1.0 cm³ of dilute nitric acid (2.0 mol/dm³). A carbonate fizzes: lead the gas into limewater and it turns milky. Then add a few drops of aqueous silver nitrate: chloride gives a white precipitate, bromide cream and iodide yellow. Or add aqueous barium nitrate: sulfate gives a white precipitate. The acid goes in first because silver and barium carbonate and sulfite are white and insoluble too. The acid removes carbonate and sulfite ions, so a precipitate that forms after it can only come from a halide or a sulfate. Every nitrate is soluble, so nitrate is found another way: warm it with aqueous sodium hydroxide and aluminium foil, and the ammonia given off turns damp red litmus blue. The nitrate test always starts on a fresh portion, because the nitric acid and the nitrate reagents bring nitrate ions of their own. Bromide is not in the lessons; its result is the textbook one.
- Precipitate, litmus and limewater colours are true colours
- Tubes are numbered on the rack; 8 is limewater
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