1. Air and Oxygen

2. What is this liquid? Where is it coming from?
On a cold morning have you ever noticed that the inside of the car window was covered in moisture?
What is this liquid?
Where is it coming from?

3. Investigation to see if there is water vapour in the air!
Wait to see what happens

4. The cobalt chloride paper changes colour from blue to pink –
Showing that there is water in the air, that condenses when it hits the cold test tube

5. Carbon dioxide (CO2) Is a colourless, odourless gas
It is special because it sublimes
How do we know that it is in air?

6. To show that there is carbon dioxide in air
Suck in here
Limewater

7. Result Eventually the limewater turns cloudy or milky in colour.
This shows that there is carbon dioxide in the air

8. Experiment

9. To show that oxygen makes up almost 1/5 of air
Steel wool
Graduated cylinder
Water trough
Leave for about one week.

10. Result One week later … The steel wool rusts.
Water rises up the cylinder to replace the oxygen used up.
Steel wool rusted
Water risen up cylinder

11. Therefore, oxygen is present in air in the proportion of one-fifth.
Why does this happen?
As the steel wool rusts, it uses up the oxygen in the air.
Water rises up the cylinder to replace the oxygen used up, to approximately 1/5th of the height of the cylinder.
Therefore, oxygen is present in air in the proportion of one-fifth.

12. The make up of air

13. Making oxygen gas (O2)
Hydrogen peroxide
Oxygen + Water
But this reaction takes a long time to happen ..
It’s very slow! 

14. A catalyst is something that changes how fast a reaction happens without getting used up itself!

15. Manganese Dioxide (MnO2)
To make this reaction happen faster we can add a catalyst.
Catalyst used:
Manganese Dioxide (MnO2)

16. A quick way to make oxygen!
Word equation:
Manganese Dioxide
Hydrogen peroxide
Oxygen + Water
Chemical equation:
Mn02
2H202
O H20

17. A quick way to make oxygen!

18. Properties of oxygen It is an odourless, colourless gas
It has a pH of 7 – it is neutral
It aids combustion (helps things to burn!)

19. A special test for oxygen!
It relights a glowing splint

20. Reactions of oxygen!

21. When an element is burned in air, a compound called an oxide is formed
Carbon + oxygen
Carbon Dioxide
Magnesium + oxygen
Magnesium oxide

22. A quick way to make oxygen!

23. Reaction of magnesium with oxygen
When magnesium reacts with oxygen we can see…
When magnesium oxide is tested with litmus paper red litmus goes ________ blue litmus goes ________
This tells us magnesium oxide is _____________

24. Reaction of carbon with oxygen
When carbon reacts with oxygen, it burns bright ____
When carbon dioxide is tested with litmus paper red litmus goes ________ blue litmus goes ________
This tells us carbondioxide is _____________

25. Uses of oxygen
1. Oxygen can be stored in cylinders to support breathing.

26. Uses of oxygen
2. WELDING!
Oxygen is used to burn metals at very high temperatures.