Water

• What type of molecule is water and why?

  Dipolar because it has both positive and negative poles. The positive pole of one water molecule is attracted to the negative pole of another water molecule.
• Why does water have a high specific heat capacity?

  It takes more energy to separate the many hydrogen bonds between water molecules. This means water buffers against temperature variations in bodies of water and inside organisms.
• Why does water have a high latent heat of vaporisation?


  It takes more energy to evaporate water and break the hydrogen bonds between water molecules. Sweat is a very efficient cooling mechanism
• Why is water good in cohesion and surface tension?

  Water molecules have hydrogen bonds which allow them to stick together - cohesion. When water meets air, water molecules tend to be pulled back into the body of water - surface tension. This means water can support certain organisms.
• Why has water got a high solubility?

  Water forms hydrogen bonds with biological molecules, which allows substances to dissolve. This means water is used in chemical reactions.
• Why does water expand when it freezes? (Not a property of water)

  Lower temperature -> lower kinetic energy -> molecules move more slowly -> more hydrogen bonds form -> water changes to a solid as molecules are packed together but spread over a large area.
• Water is a metabolite in metabolic reactions e.g. hydrolysis and condensation, which are used in the formation and breaking of chemical bonds
• What features does water have?

  Cohesion & surface tension, specific heat capacity, latent heat of vaporisation, solubility, metabolite