Monday, November 28, 2011

Chapter 5: The Air Around Us

The Composition of Air

Earth has a layer of Air
– atmosphere – protects living things on earth from harmful rays

Air – colourless, tasteless and odourless – mixture of many components
Nitrogen (78%)
-Inactive gas
-Does not burn – does not allow things to burn in it
-Dilutes the oxygen in the air so that processes such as respiration, burning and decay slows down

Oxygen (21%)
-Used during respiration, burning, decay and rusting
-Required for living things to survive
-Set free during photosynthesis
-Respiration - Process of oxidising (burning) digested food in the cells of the body to produce energy, carbon dioxide and water
Glucose + Oxygen = Energy + Carbon Dioxide + Water

-Combustion – Chemical reaction that takes place when a substance combines with oxygen and produces an oxide, heat ebergy or light energy

Rare gases (0.9%)

-Helium, neon, argon – inactive but have their own purposes

Carbon Dioxide (0.03%)
-Released during respiration, burning and decay
-Used for photosynthesis

Water vapour and microorganisms
-Bacteria, fungi, dust

Air Pollution

• The addition of unwanted substances to the air (pollutant) causes air pollution
• Main pollutants – Dust, smoke, Carbon dioxide, Carbon monoxide, sulphur oxide, nitrogen oxide
• Harmful effects of air pollution
- Health problems
-Depletion of food resources
- Destructio of habitat
-Extinction of species
-Destruction of property
-Global warming
-Thinning of ozone layer

Click on the below link for videos on Air Pollution
Air Pollution

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