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CHAPTER 5

CHAPTER 5. The composition of air. Air is a mixture of various substances that is odourless , colourless , or tasteless Water vapour in the air depends on the humidity in the air. The more humid the air, the more the water vapour in the air Examples of inert gases are : Dust

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CHAPTER 5

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  1. CHAPTER 5 The composition of air

  2. Air is a mixture of various substances that is odourless, colourless, or tasteless • Water vapour in the air depends on the humidity in the air. • The more humid the air, the more the water vapour in the air • Examples of inert gases are: • Dust • Water vapour • Microorganisms The composition of air

  3. Air is made up of three main gases: oxygen, carbon dioxide and nitrogen • Each gas has its own chemical properties • The properties of the gases can be observed by : • Solubility in the water • Reaction with sodium hydroxide • Effects on • Glowing wooden splinter • Burning wooden splinter • Litmus paper • Lime water • Hydrogen carbonate indicator Nitrogen is a gas that does not react chemically The properties of oxygen and carbon dioxide

  4. Air that is breathed into the body is called inhaled air • Air that is breathed out of the body is called exhaled air • Oxygen is needed for respiration: • Inhaled oxygen will be dissolved at the surface of the moist alveolus. • Oxygen will be absorbed into the blood capillary through the thin alveolus wall • Oxygen is then transported by red blood cells to the other blood cells for the process of respiration • At the same time, carbon dioxide and water from blood capillaries will be absorbed alveolus. • Carbon dioxide and water will be expelled body when air is exhaled. Oxygen is needed for respiration

  5. Combustion is a process that takes place when a substance unites with oxygen chemically and this produces energy and light. • Without oxygen. Combustion cannot occur because chemical process does not take place. • Carbon is a chemical compound that is made up of the carbon element only • Combustion of carbon releases carbon dioxide, heat energy and light energy. • Examples of carbon are wood, cloth, charcoal, and paper. • Carbon + OxygenCarbon dioxide + Heat energy + Light energy • Hydrocarbon is a chemical compound which is formed from only hydrogen and carbon. Oxygen is needed for combustion

  6. Combustion of hydrocarbon produces carbon dioxide, water, heat energy and light energy. • Water is formed when hydrogen from hydrocarbon combines with oxygen during combustion. • Hydrocarbon + Carbon Carbon Dioxide +Water +Heat energy + Light energy • Combustion produces light energy and heat energy • Carbon dioxide produced is absorbed by green plants to conduct photosynthesis. Oxygen is needed for combustion(CONTINUE)

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