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Topic 1: Chemical Tests, Ions to remember, Gas tests, Solubility, Flame…
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Gas tests
Oxygen test - Light a splint on fire then extinguish the flame. Immediately dip the splint into the gas.
Positive result : The glowing splint will relight since oxygen is a supporter of combustion
Hydrogen test - Light a splint on fire and dip it into the hydrogen gas
Positive result : "Squeaky pop" sound occurs
Carbon Dioxide test - Transfer gas from boiling tube into tube of lime water using delivery tube
Positive result : Limewater will turn a milky white since it reacts to form chalk (CaCO3)
Chlorine test - Use blue litmus paper for the test
Positive result : Paper turns red and then it bleacher(turns white)
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Solubility
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Vocabulary :
- Soluble: Something that can be dissolved into a liquid
- Insoluble: Something that cannot be dissolved into a liquid
- Solvent: The liquid that the solid is being dissolved in
- Solute: The thing being dissolved in the liquid
- Solution: The product
- Precipitate: When to solutions are mixed and react to form an insoluble solid product (often a salt) called a precipitate
Insoluble :
- Common carbonates (except group 1 elements & ammonium)
- Common hydroxides (except sodium, potassium, ammonium)
Soluble :
- Common sodium, potassium, ammonium salts
- All nitrate salts
- Common halides(Halogens: group 7 elements) (except silver and lead)
- Common sulfates (except barium, calcium and lead)
Flame tests
Instructions :
- Dip nichrome wire loop in dilute HCl to clean it
- Dip into metal you want to test
- Hold in the hottest part of the fire
- Note color of flame
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Notes :
- Nichrome wire is used since it doesn’t change the color of the flame so we know the flame color changes from the metal being tested (Platinum can also be used)
- Hydrochloric acid is used to sanitize the nichrome wire. This is because HCL turns the metal into a metal chloride making it volatile(easy to boil)
- You cannot use safety flame because it is orange so you must use the strongest flame on the Bunsen burner.
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Water test
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Chemical test for any water : You can use copper sulfate to test for water.
- Put a few drops of water onto white anhydrous copper sulfate
- The water should turn the copper sulfate blue. This makes it into hydrated copper sulfate
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