Water

• 9 Properties of water:

  1. cohesive
  2. adhesive
  3. high surface tension
  4. high specific heat capacity
  5. solid water is less dense than liquid water
  6. water organises non-polar molecules
  7. high heat of vaporisation
  8. forms ions
  9. excellent solvent
• cohesive


  water molecules stick to other water molecules via hydrogen bonding
• adhesive 


  water molecules stick to other polar molecules via hydrogen bonding
• high surface tension 


  where water meets air

  small insects can "walk" on water

  droplets on trees
• high specific heat capacity 


  a large amount of energy is needed to change the temperature of water

  temperature of a body of water remains fairly constant compared to air temperature

  protects organisms in water from sudden changes in temperature
• Density of solid vs liquid water

  Bodies of water freeze from the top down

  Provides insulation for organisms living under the ice - prevents them from being stranded on the surface

  Ice on top provides a habitat
• Water organises non-polar molecules 


  Hydrophilic - water-loving

  Hydrophobic - water-hating - water causes hydrophobic molecules to aggregate and form specific shapes to avoid water e.g. bilipid layer
• high heat of vaporisation 


  the evaporation of water from a surface causes cooling of that surface
• forms ions 


  H+ ions and OH- ions
• excellent solvent 


  water dissolves polar molecules, charged ions and some non-polar molecules

  essential medium for many biological and chemical reactions