1. © Edco 2010 Exploring Science Chemistry Chapter 27 – The Atmosphere Air Air is a mixture of gases. — Nitrogen (N 2 ) makes up almost 4/5 of air. — Oxygen (O 2 ) makes up almost 1/5 of air.

2. © Edco 2010 Exploring Science Chemistry Composition of air Chapter 27 – The Atmosphere

3. © Edco 2010 Exploring Science Chemistry Experiment To show that oxygen makes up almost 1/5 of air Chapter 27 – The Atmosphere

4. © Edco 2010 Exploring Science Chemistry Method To show that oxygen makes up almost 1/5 of air Pack some steel wool into the bottom of a graduated cylinder. Invert the cylinder in a basin of water. Leave for about one week. Measure the height that the water rises up the cylinder. Chapter 27 – The Atmosphere

5. © Edco 2010 Exploring Science Chemistry Result To show that oxygen makes up almost 1/5 of air One week later … The steel wool rusts. Water rises up the cylinder to replace the oxygen used up. Chapter 27 – The Atmosphere

6. © Edco 2010 Exploring Science Chemistry Conclusion To show that oxygen makes up almost 1/5 of air 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 1/5 th of the height of the cylinder. Chapter 27 – The Atmosphere

7. © Edco 2010 Exploring Science Chemistry Experiment To show that there is carbon dioxide in air Chapter 27 – The Atmosphere

8. © Edco 2010 Exploring Science Chemistry Method To show that there is carbon dioxide in air Set up the apparatus as shown in the diagram. Air is bubbled through the clear limewater. Chapter 27 – The Atmosphere

9. © Edco 2010 Exploring Science Chemistry Result To show that there is carbon dioxide in air Eventually the limewater turns cloudy or milky in colour. Chapter 27 – The Atmosphere

10. © Edco 2010 Exploring Science Chemistry Conclusion To show that there is carbon dioxide in air The only gas that causes limewater to turn from clear to milky in colour is carbon dioxide. Chapter 27 – The Atmosphere

11. © Edco 2010 Exploring Science Chemistry Experiment To show there is water vapour in the air Chapter 27 – The Atmosphere

12. © Edco 2010 Exploring Science Chemistry Method To show there is water vapour in the air Fill a test tube with ice and stopper it. Dry the outside of the test tube. When you see a liquid has formed on the outside of the glass, place a piece of cobalt chloride paper against the test tube. Chapter 27 – The Atmosphere

13. © Edco 2010 Exploring Science Chemistry Result To show there is water vapour in the air The cobalt chloride paper changes colour from blue to pink. Chapter 27 – The Atmosphere

14. © Edco 2010 Exploring Science Chemistry Conclusion To show there is water vapour in the air Cobalt chloride paper changes colour from blue to pink only when water is present. Chapter 27 – The Atmosphere

15. © Edco 2010 Exploring Science Chemistry Experiment To prepare and examine oxygen gas Chapter 27 – The Atmosphere

16. © Edco 2010 Exploring Science Chemistry Equation To prepare and examine oxygen gas Chapter 27 – The Atmosphere

17. © Edco 2010 Exploring Science Chemistry Apparatus To prepare and examine oxygen gas Chapter 27 – The Atmosphere

18. © Edco 2010 Exploring Science Chemistry Properties of oxygen gas Oxygen gas is a colourless, odourless gas. Oxygen gas relights a glowing splint. Oxygen gas supports combustion. Oxygen gas is a neutral gas. Chapter 27 – The Atmosphere

19. © Edco 2010 Exploring Science Chemistry Experiment Preparation of carbon dioxide gas Chapter 27 – The Atmosphere

20. © Edco 2010 Exploring Science Chemistry Equation Preparation of carbon dioxide gas Chapter 27 – The Atmosphere

21. © Edco 2010 Exploring Science Chemistry Apparatus Preparation of carbon dioxide gas Chapter 27 – The Atmosphere

22. © Edco 2010 Exploring Science Chemistry Properties of carbon dioxide gas Carbon dioxide gas causes limewater to turn from clear to milky in colour Chapter 27 – The Atmosphere

23. © Edco 2010 Exploring Science Chemistry Equation Chapter 27 – The Atmosphere

24. © Edco 2010 Exploring Science Chemistry Properties of carbon dioxide gas Carbon dioxide gas does not support combustion and is more dense than air. Carbon dioxide gas is acidic. Carbon dioxide gas is colourless and odourless. Chapter 27 – The Atmosphere

25. © Edco 2010 Exploring Science Chemistry Uses of carbon dioxide. Chapter 27 – The Atmosphere