Water

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Water for life

  • Acts as a medium for chemical reactions 
    • Many of the solutes in an organism can be dissolved because water is polar = a solvent 
    • Cytosol is made up of mainly water 
  • Efficient Transport Medium
    • Adhesion & cohesion = capillary action (water rising up a narrow tube against the force of gravity 
  • Coolant 
    • Heat energy isn't escaping into surrounding because it's being absorbed which allows a constant temp. meaning enzymes (which work in a narrow temp. range) can work efficiently still
  • Stable
    • Ice floats - forms an insulating layer - aquatic creatures couldn't survive in freezing temperatures
  • Surface tension 
    • strong enough to support small insects such as pond skaters
  • Transparent
    • allows light through so plants can still get light and photosynthesise
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Characteristics

  • High Boiling point
    • Due to hydrogen bonds
    • Requires a lot of energy to increase temp. of water due to the bonds absorbing the energy 
  • Ice is less Dense 
    • Because of hydrogen bonds 
    • They fix the positions of the polar molecules slightly further parat 
    • The hydrogen bonds form it into a lattice where every oxygen is at the centre of a tetrahedral arrangement
  • Cohesive
    • Attracted to each other which creates usrface tension
  • Adhesive 
    • Attracted to other material
  • Polar 
    • Uneven distrbution of electrons on the covalent bond 
    • slight charges on oxygen and hydrogen causes electrostatic attraction
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