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Science form 1(Chapter5-part2)

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  1. 1. SCIENCE Form 1 UNIT 5 : The Air Around Usyschow@smkbpj(a) 1
  2. 2. 5.1 The Composition of Air• The Earth’s surface is surrounded by a larger of air known as atmosphere• Air is a mixture of various substances which is tasteless, colourless and odourless but we can feel it through wind when it moves yschow@smkbpj(a) 2
  3. 3. • Nitrogen, oxygen, carbon dioxide and inert gases have a fixed percentage of component in the mixture of air yschow@smkbpj(a) 3
  4. 4. • Other substances such as dust, microorganisms and water vapour can also be found in the air but their contents vary depends on the quality of air of that environment yschow@smkbpj(a) 4
  5. 5. Inert gas / noble gas Krypton for fluorescent bulbs.Helium Xenon For sun lamps yschow@smkbpj(a) Neon for light 5 For earthquake prediction
  6. 6. To determine the percentage of oxygen in air• As the candle continue to burn the flame get smaller and finally it goes off.• The water lever increases and occupied the space of oxygen in the gas jar.Conclusion: Oxygen makes up of approximately 21% of the volume of air. yschow@smkbpj(a) 6
  7. 7. Air contains water vapour• Water droplets that formed on the outer wall of the test tube can be clearly seen.• Collect the liquid droplets and test with a blue cobalt chloride paper. The paper then turns to pink in colour, this proofs that the liquid is water.Conclusion• Air contains water vapour. yschow@smkbpj(a) 7
  8. 8. Air contains microorganisms Coloured spots of microorganisms (fungi) are found on the surface of the nutrient agarConclusion:Air contains microorganisms. yschow@smkbpj(a) 8
  9. 9. Air contains dust Dust can be seen on the sticky surface of glass slide.Conclusion :Air contains dust. yschow@smkbpj(a) 9
  10. 10. Exercise 5.1 yschow@smkbpj(a) 10
  11. 11. 21 % 78 % 0.03 % 0.97 %yschow@smkbpj(a) 11
  12. 12. 5.2 The Properties of Oxygen and Carbon Dioxide• Oxygen and carbon dioxide are the two main gases that made up the air for sustaining life• The properties of gases can be studied and observed by carrying out the following tests yschow@smkbpj(a) 12
  13. 13. Test 1: Solubility in waterOxygen Carbon dioxide• The water level in the test • The water level in the test tube rises slightly tube rises a lot.• Oxygen only dissolve a little • Carbon dioxide is soluble in in water water yschow@smkbpj(a) 13
  14. 14. Test 2: Reaction with sodium hydroxideOxygen Carbon dioxide• The level of sodium • The level of sodium hydroxide solution in the hydroxide solution in the test tube does not change test tube rises a lot• Oxygen is not soluble in • Carbon dioxide is very sodium hydroxide soluble in sodium hydroxide yschow@smkbpj(a) 14
  15. 15. Test 3: Glowing wooden splinterOxygen Carbon dioxide• The glowing wooden • The glowing wooden splinter bursts into flame splinter extinguished• Oxygen helps in combustion • Carbon dioxide does not help in combustion yschow@smkbpj(a) 15
  16. 16. Test 4 : Burning wooden splinterOxygen Carbon dioxide• The burning wooden • The burning wooden splinter burns brightly splinter extinguished• Oxygen supports • Carbon dioxide does not combustion supports combustion yschow@smkbpj(a) 16
  17. 17. Test 5: Tested with moist litmus paperOxygen Carbon dioxide• The colour of both litmus • The colour of blue litmus paper does not change paper turns red• Oxygen is neutral • Carbon dioxide is acidic yschow@smkbpj(a) 17
  18. 18. Test 6: Lime water testOxygen Carbon dioxide• No change • The lime water turns chalky yschow@smkbpj(a) 18
  19. 19. Test 6: Bicarbonate indicator testOxygen Carbon dioxide• The red colour of indicator • The red colour of indicator does not change turns yellow• Oxygen in neutral • Carbon dioxide is acidic yschow@smkbpj(a) 19
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  21. 21. yschow@smkbpj(a) 21