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Chemical Tests (Gas Tests (Carbon Dioxide (Since carbon dioxide is heavier…
Chemical Tests
Flame Tests
When performing a flame test, there are a few steps you need to perform before you tart the test:
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Gas Tests
Hydrogen
To test for hydrogen, you can first add and acid and a metal to a boiling tube. This should produce hydrogen.To test that this is hydrogen, put a lit wooden splint into the boiling tube and it should make a squeaky pop sound if hydrogen present.
Ammonia
Ammonia gas will turn damp red litmus paper blue and also gives off a choking smell. The reason why the litmus paper needs to be damp is so the ammonia gas is able to dissolve into the litmus.
Oxygen
To test for oxygen, you can put a glowing splint into a test tube. If enough oxygen is present, the splint should relight. This is because oxygen is part of the fire triangle and is needed for combustion.
Carbon Dioxide
Since carbon dioxide is heavier than air, it can be poured on a lit splint and it will go out
Carbon dioxide is a product of respiration, therefore if you exhale, carbon dioxide is produced. When carbon dioxide is bubbled through lime water, it turns cloudy. This is because a precipitate forms. After excess carbon dioxide is bubbled through the lime water, it should return to a clear colour.
Chlorine
To test for chlorine you can use a piece of damp blue litmus paper. The gas should dissolve into the water and turn the paper red, then bleach it white.
Testing for water
Water will turn anhydrous copper sulphate, a white powder, into hydrated copper sulphate, blue crystals
Testing for Anion
Halide Anions
Bromide
Adding nitric acid, then silver nitrate should produce a cream precipitate
Iodide
Adding nitric acid, then silver nitrate should produce a yellow precipitate
Chloride
Adding nitric acid, then silver nitrate should produce a white precipitate
Sulphate Anions
Reacting Sodium sulphate and barium chloride should produce barium sulphate and sodium chloride. Barium sulphate is a white solid, so a white precipitate should be observable from this reaction.
Carbonate Anions
Metal carbonates produce carbon dioxide gas when reacted with HCl. Carbon dioxide can be tested for using lime water, which should turn milky when carbon dioxide is bubbled through it. Excess carbon dioxide will cause it to return to colourless.
Testing for Cation
Non-Metal Cations
Ammonium
Reacting Ammonium and Sodium hydroxide together and then heating the products will produce Ammonia gas. Ammonia gas can be tested for using damp red litmus paper. Ammonia gas will turn damp red litmus paper blue.
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