Identifying Ions
This practical lesson covers:
- How to identify unknown ions through chemical tests
Investigating ions present in a sample by completing chemical tests
Aim
The aim of this practical is to identify ions present in an unknown solution by completing chemical tests.
Background information
Chemical tests are used to determine the ions present in unknown solutions by observing whether they give a positive or negative result. In this practical you will be doing the tests below and looking for the following positive results:
- Flame test - Identifies metal ions by the colours they produce when heated.
- Carbonate test - Test for carbon dioxide by turning limewater cloudy.
- Sulfates test - Barium chloride forms an insoluble white precipitate when sulfates are present.
- Halides test - Halides produce coloured silver halide precipitates when reacted with silver nitrate solution.
What identifies metal ions in a flame test?
the sound they produce when heated
the colours they produce when heated
the smell they produce when heated
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What is the carbonate test used for?
test for oxygen by turning limewater clear
test for carbon dioxide by turning limewater cloudy
test for hydrogen by turning limewater yellow
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What happens when sulfates are present in the sulfates test?
barium chloride forms a soluble white precipitate
barium chloride forms a soluble black precipitate
barium chloride forms an insoluble white precipitate
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What do halides produce in the Halides test?
halides produce colourless silver halide precipitates when reacted with silver nitrate solution
halides produce coloured gold halide precipitates when reacted with silver nitrate solution
halides produce coloured silver halide precipitates when reacted with silver nitrate solution
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What is used to identify ions present in an unknown solution?
biological tests
chemical tests
physical tests
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What is used to test for carbon dioxide in the carbonate test?
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What forms an insoluble white precipitate when sulfates are present in the sulfates test?
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