Paper 1 - Chemical Tests Flashcards
Describe the test for hydrogen gas
- Burn a lighted splint in hydrogen gas
- Should produce a squeaky pop noise if the gas is hydrogen
Describe the test for oxygen gas
- Burn a glowing splint in oxygen gas
- The splint should relight if the gas is oxygen
Describe the test for carbon dioxide gas
- Bubble carbon dioxide gas through limewater
- Lime water should turn cloudy if the gas is carbon dioxide
Describe the test for chlorine gas
- Place damp blue litmus paper in chlorine gas
- Litmus paper should initially turn red but then turn white if it is chlorine gas
Describe the test for ammonia gas
- Place damp red litmus paper in ammonia gas
- Litmus paper should turn blue if the gas is ammonia
Describe how to carry out a flame test
- Dip a platinum wire loop into dilute HCl to clean it
- Hold the platinum wire loop in a flame - it will burn with no colour
- Then dip the platinum wire loop into the sample that is being tested
- Then place back in the clear blue part of the Bunsen flame
What colour is formed in the flame test of Li+
Red
What colour is formed in the flame test of Na+
Yellow
What colour is formed in the flame test of K+
Lilac
What colour is formed in the flame test of Ca2+
Orange-Red
What colour is formed in the flame test of Cu2+
Blue-Green
Describe the test for NH4+ using sodium hydroxide solution and identify the gas produced
- add sodium hydroxide
- will produce ammonia gas
- Test for Ammonia gas using a damp piece of red litmus paper - the litmus paper will turn from red to blue
Describe the test for Cu2+ using sodium hydroxide solution and identify the gas produced
- Add Aqueous Sodium Hydroxide
- The colour of the precipitate will be Blue
- Hydrogen gas produced
Describe the test for Fe2+ using sodium hydroxide solution
- Add Aqueous Sodium Hydroxide
- The colour of the precipitate will be Sludgy Green
Describe the test for Fe3+ using sodium hydroxide solution
- Add Aqueous Sodium Hydroxide
- The colour of the precipitate will be Red-Brown
Describe the test for Cl- using acidified silver nitrate solution and identify the gas produced
- Add nitric acid to remove impurities such as carbonate ions
- Add silver nitrate solution
- A chloride gives a white precipitate of silver chloride
Describe the test for Br- using acidified silver nitrate solution
- Add nitric acid to remove impurities such as carbonate ions
- Add silver nitrate solution
- A bromide gives a cream precipitate of silver bromide
Describe the test for I- using acidified silver nitrate solution and identify the gas produced
- Add nitric acid to remove impurities such as carbonate ions
- Add silver nitrate solution
- An iodide gives a yellow precipitate of silver iodide
Describe the test for SO4 2- using acidified barium chloride solution and identify the gas produced
- Add hydrochloric acid to remove impurities such as carbonate ions
- Add barium chloride solution
- A white precipitate of barium sulphate forms means the original compound was a sulphate
Describe the test for CO3 2- using hydrochloric acid and identify the gas produced and identify the gas produced
- Add hydrochloric acid
- If carbonate ions are present, fizzing will occur
- Bubble CO2 gas produced through limewater
- Limewater should turn cloudy if the gas is CO2
Describe a test for the presence of water using anhydrous copper(II) sulfate
- When Cu(II) Sulfate is bound to water, it forms blue crystals
- Heat the blue hydrated Cu(II) Sulfate to evaporate the water
- This leaves white anhydrous Cu(II) Sulfate powder
- Add 3 drops of water to the white powder to form the blue crystals
Describe a physical test to show whether a sample of water is pure
- Heat water to exactly 100℃ and if it boils, it is pure
- Cool water to 0℃ and if it freezes, it is pure
