1. TESTS FOR GASES
& WATER

2. Limewater is a solution of the alkali, calcium hydroxide, Ca(OH)2
LAB. TEST FOR CARBON DIOXIDE GAS.
CO2
Limewater is a solution of the alkali, calcium hydroxide, Ca(OH)2
Limewater solution
When carbon dioxide reacts with limewater, it makes the solution go milky
(insoluble particles of calcium carbonate are being made)

3. A GLOWING splint RELIGHTS in oxygen gas
LAB. TEST FOR OXYGEN GAS.
Oxygen gas
A GLOWING splint RELIGHTS in oxygen gas
This is because oxygen promotes combustion – the wood burns more readily in oxygen than in air

4. LAB. TEST FOR HYDROGEN GAS.
A LIGHTED splint gives a SQUEAKY POP in hydrogen gas
This is from the reaction between hydrogen and oxygen
– it is a mini-explosion!

5. LAB. TEST FOR CHLORINE GAS.
Damp blue litmus paper turns RED then BLEACHES
The litmus turns RED because chlorine is acidic
Then it turns WHITE because chlorine is a bleach
You can also recognise it from its SWIMMING POOL smell

6. LAB. TEST FOR AMMONIA GAS.
Damp red litmus paper turns BLUE
The litmus turns BLUE because ammonia is ALKALINE
You can also recognise it from its pungent SMELL

7. LAB. TEST FOR ACIDIC GASES (eg SO2, HCl)
Damp blue litmus paper turns RED
This doesn’t tell you WHICH acidic gas you have
Note the difference from chlorine – chlorine BLEACHES it too

8. The reaction gives off a lot of HEAT as well
LAB. TEST FOR WATER
Water turns white anhydrous copper sulphate to blue hydrated copper sulphate
White anhydrous copper sulphate
The reaction gives off a lot of HEAT as well
To show the water is PURE, you’d show it boiled at 100oC