Chap 5.1

• Boiling point of pure water


  100C
• Freezing point of pure water


  0C
• Physical characteristics of pure water

  • Colourless
  • Density = 1 g cm^-3
• Effects of absorption and release of heat on the state of water

  1. Heat is absorbed: melting, evaporation/boiling

  2. Heat is released: condensation, freezing, sublimation
• Composition of water

  Water is a compound which is made up of 2 hydrogen atoms and 1 oxygen atom
• Determining the composition of elements in a water molecule

  Through electrolysis: oxygen gas produced at anode, hydrogen gas at cathode
• Evaporation of water


  The process that happens at the surface of water that changes water to water vapour
• Factors affecting the rate of evaporation

  • Humidity
  • Surrounding temperature
  • Exposed surface area of water
  • Movement of air
• Applications of evaporation of water in daily life


  • Clothes hung on clothes lines dry faster
  • Sea salt is obtained from the evaporation of seawater
  • Seafood that is dried can be kept longer as microorganisms cannot survive without water