4.6 Chemical Analysis Flashcards
What is the gas test for hydrogen?
Squeaky Pop Test:
- Collect sample of gas in test tube
- Attempt to ignite gas using lit splint
result: Squeaky pop sound
What is the gas test for oxygen?
Glowing Splint Test:
- Collect sample of gas in test tube
- Place a glowing splint into test tube
Result: Splint relights
What is the test for presence of water?
- Add anhydrous copper(II) sulphate
Result: Colour changes from white to blue
What is the test for water purity?
- Measure its boiling point
Result: Closer to 100°C = more pure
What is the test for carbon dioxide?
- Bubble sample of gas through limewater
Result: A white precipitate forms (turns cloudy)
What is the test for chlorine?
Damp Blue Litmus Test:
- Place damp blue litmus paper in a sample of gas
Result: It turns white (bleaches)
What is the test for ammonia?
Damp Red litmus Test:
- Place damp red litmus in gas sample
Result: It turns blue
Why does red litmus turn blue in the test for ammonia?
The OH- ions ae what left after the H2O has lost H+, and are alkaline
Why does blue litmus go white in test for chlorine?
Cl2 is a good bleaching agent, so easily removes colour from substance
Why does limewater form a white precipitate when testing for carbon dioxide?
Limewater is saturated calcium hydroxide solution, and forms a white calcium carbonate when reacted with O2
Why does splint relight when testing for oxygen?
Pure O2 is more concentrated than the O2 in normal air, meaning wood relights because combustion takes place faster
Why is a POP sound heard when testing for hydrogen?
Air rushes out of the test tube
