water

• functions of water

  solvent

  dissolve polar substances

  medium for chemical reactions

  transport medium

  coolant

  habitat
• what happens when you add salt to the water

  NaCl dissociats

  gets surrounded by H2O molecules

  orient so delta pos H faces the neg charge and delta neg O faces the pos

  until water is saturated
• why is a water molecule presented in a v shape

  2 lone pairs of electrons in oxygens outer shell and like charges repel
• what polar region is O

  delta neg
• what polar region is H

  delta pos
• how do you draw a hydrogen bond

  as a broken line

  weak bond
• why is water a good coolant

  because it has a high SHC so will absorb a lot of energy before evaporating
• why is waters SHC good for aquatic life

  very high

  so will maintain a relatively constant temp

  ie a stable aquatic environment
• what is surface compression

  strong cohesion between water molecules

  relatively evenly spaced out across a molecule but not the water molecules at the top as they wont have water molecules to form bonds with above them - no upwards force is exerted

  this forms a top layer of compression

  so things can float on water
• why does ice float on water

  as water cools it has less KE

  less H bonds are broken

  resulting in ice being less dense then water
• why does the way water freezes benefit aquatic life

  freezes from the top down

  creates a layer of insulation at the top
• why does oil not mix well with water

  oil is non polar

  but for oil to interact with something there needs to be a slight difference in charge

  so water does not interact with lipids as no hydrogen bonds form