1. 2e) Oxygen and oxides

2. Air 78% Nitrogen 21% Oxygen 0.93% Argon and other noble gases 0.04% carbon dioxide Variable amounts of water vapour Variable amounts of pollutant gases

3. Oxygen Extracted from air by fractional distillation If air is cooled down, at -183°C oxygen condenses into a liquid (at -196°C Nitrogen condenses too)

4. Burning magnesium magnesium + oxygen magnesium oxide reactantsproduct +

5. Heating other metals Heating copper in air

6. Burning copper copper + oxygencopper oxide reactantsproduct +

7. Copper and air

8. Iron and air

9. The amount the water rises indicates the percentage oxygen in the air

10. Methane and oxygen methane + oxygencarbon dioxide + water CH 4(g) + 2O 2(g) CO 2(g) + 2H 2 O (g)

11. Carbon and oxygen Carbon burns producing carbon dioxide and water C + O 2 CO 2 + 2H 2 O

12. Sulphur dioxide SO 2 Produced by burning sulphur (or burning fossil fuels) S (l) + O 2(g) SO 2(g)

13. In water Dissolves to form sulphurous acid SO 2(g) + H 2 O (l) H 2 SO 3(aq)

14. With an alkali Forms a sulphite SO 2 + 2NaOHNa 2 SO 3 + H 2 O

15. Carbon dioxide

16. Preparing carbon dioxide Acid + carbonate salt + water + carbon dioxide 2HCl + CaCO 3 CaCl 2 + H 2 O + CO 2

17. In water Dissolves to form carbonic acid CO 2(g) + H 2 O (l) H 2 CO 3(aq) pH 5.5

18. In alkali H 2 CO 3(aq) + 2NaOH (aq) Na 2 CO 3(aq) + 2H 2 O (l) acid + basesalt + water

19. Uses of carbon dioxide Fizzy drinks. The higher the pressure, the more soluble the gas becomes. So what happens when the pressure is released?

20. Uses of carbon dioxide Fire extinguishers How does it work?

21. Uses of carbon dioxide Dry ice (actually it’s condensed water vapour that you can see.)

22. Oxides of nitrogen Nitrogen is generally an unreactive gas, and needs fairly extreme conditions to get it to react with oxygen

23. Nitric oxide, NO Lightning brings about the direct union of nitrogen and oxygen in the air to produce small amounts of nitric oxide, as does the high temperatures produced in car engines.

24. Nitric oxide, NO It is a toxic air pollutant, often linked with asthma and allergic responses

25. Nitrogen dioxide, NO 2 In the presence of excess oxygen, nitric oxide, NO, will be converted to nitrogen dioxide,NO 2. Nitrogen Dioxide is a reddish brown, toxic gas at room temperature. NO 2 condenses to a brown liquid, but freezes to a colourless solid.

26. Nitrogen dioxide, NO 2 Nitrogen Dioxide has been used as a catalyst in certain oxidation reactions; as a nitrating agent for organic compounds; as an oxidizing agent; as a rocket fuel; and as a flour bleaching agent

27. Nitrous oxide, N 2 O Formed when ammonium nitrate, NH 4 NO 3, is heated. A colourless gas with a pleasing odour and sweet taste, is used as an anesthetic for minor operations, especially in dentistry. You don’t need to know about this!

28. Nitrous oxide, N 2 O It is called laughing gas because of its intoxicating effect. It is also widely used as a propellant in aerosol cans of whipped cream!

29. A reminder!

30. Rusting Rust is a form of iron oxide. It has water bonded loosely to it. It is called hydrated iron oxide

31. In order for iron to rust Both air and water’s a must, Air alone won’t do Without water there too, So protect it, or get a brown crust! It’s actually the oxygen in air

33. Protecting from rust

34. Protection methodHow it works PaintBarrier Vaseline/oilBarrier SiliconeBarrier Zinc (Galvinising)Sacrificial

35. Sacrificial protection

36. Zinc is electrically connected to the iron. Any water or oxygen reacts with the zinc (or magnesium) instead of the iron. Coating in zinc is called galvanization and it works even when the zinc coating is scratched.