m,,,,

• Water pollution


  Befouling of water due to man-made or artificial chemicals
• Test for pure water


  1. Add water to cobalt chloride paper - colour changes from blue to pink

  2. Add water to anhydrous copper(II)sulphate - colour changes from white to blue
• Pure water has a fixed boiling point and impurity increases the boiling point of water
• Impurity decreases melting point of water (ice)
• Distilled water


  More suitable for experiments due to its purity and lack of dissolved impurities
• Impurities in water


  • Beneficial: Dissolved oxygen, Mineral ions/Salts/Metal compounds
  • Harmful: Microbes, Nitrates from Fertilizers, Phosphates from Fertilizers and Detergents, Pesticides, Metal ions/Metal Compounds, Sewage waste, Plastic, Industrial waste
• Microbes cause various diseases when they enter into the body
• Nitrates and Phosphates cause deoxygenation of water leading to death of aquatic life (Eutrophication)
• Sewage waste is toxic and contains microbes that cause diseases
• Some Metal Compounds are toxic
• Desalination


  Removal of soluble salts from water
• Purification of water


  1. Chlorine is added to kill germs

  2. Activated Carbon/Charcoal is used to remove bad odour and taste by absorbing impurities

  3. Insoluble impurities are removed by filtration

  4. Sedimentation is a common way of treating water - it removes solids that float and settle
• Eutrophication


  1. Addition of Phosphates and nitrates to water (from Fertilizers)

  2. Promotion of growth of Algae

  3. Algae absorb light and oxygen and prevent it - decreases oxygen content of water

  4. Lack of oxygen and light causes death of aquatic life
• Fertilizers


  Substances that provide nutrients to plants for better growth - Nitrogen, Phosphorous and potassium are the most important
• Ammonium salts


  Very good fertilizers as they contain high amount of nitrogen and are easily soluble in water
• Composition of air


  • Nitrogen: 78%
  • Oxygen: 21%
  • Carbon dioxide: 0.03%
  • Argon: 0.93%
• Liquid air


  Separated into its components by fractional distillation based on boiling point
• Air pollutants


  • Carbon monoxide, Carbon dioxide (Greenhouse gas), Oxides of Sulphur, Oxides of Nitrogen, Methane (Greenhouse gas), Chlorofluorocarbons (CFCs), Unburnt Hydrocarbons, Particulates
• Carbon monoxide


  Poisonous gas that decreases oxygen carrying capacity of Hemoglobin
• Carbon dioxide


  Greenhouse gas that causes global warming
• Oxides of Sulphur


  Cause acid rain
• Oxides of Nitrogen


  Cause acid rain
• Methane


  Greenhouse gas more dangerous than carbon dioxide
• Chlorofluorocarbons (CFCs)


  Cause ozone layer depletion
• Acid rain formation


  1. Oxides of nitrogen or sulphur mix with rain water

  2. Sulphur dioxide combines with oxygen to form sulphur trioxide which mixes with rain water to form acid rain

  3. Oxides of nitrogen from internal combustion engines also produce acid rain
• Acid rain damages buildings and causes leaching and death of aquatic life
• Flue gas desulphurization


  CaCO3 or CaO is used to remove sulphur dioxide from industrial waste gas
• Catalytic converter


  Reduces oxides of nitrogen and carbon monoxide, forming carbon dioxide and nitrogen
• Ozone layer


  Filters UV radiation from the sun, but ozone in lower atmosphere is poisonous
• Ozone layer depletion


  Caused by chlorine in CFCs
• Greenhouse effect


  Trapping of heat energy in earth and prevention from escaping into earth's surface, caused by carbon dioxide and methane
• Global warming


  Increase in temperature of the earth due to greenhouse effect
• Methane is a more dangerous greenhouse gas than carbon dioxide
• Carbon cycle


  Carbon enters atmosphere via combustion and respiration as carbon dioxide, and is removed by photosynthesis
• Carbon cycle is disturbed by human activities causing increase in carbon dioxide
• Renewable energy resources


  Energy resources that can be used again and again, do not cause pollution, and are environmentally friendly (e.g. solar, wind)
• Non-renewable energy resources


  Will deplete after a certain time, present in finite amount, and cause pollution (e.g. fuels, gas)
• Photosynthesis


  Carbon dioxide + Water -> Glucose + Oxygen, requires light and chlorophyll