Water

Question 1

describe the polarity of a water molecule

Answer 1

• dipolar molecule > has two charged ends
  hydrogen is slightly positive
  oxygens are slightly negative

Question 2

why is water a good solvent

Answer 2

• water is polar
• so it is a good solvent for polar substances
• negatively charged atoms in substances will be attracted to the hydrogen
• positively charged atoms will be attracted to the oxygen
• this means the substance breaks apart

Question 3

which substances can water not dissolve

Answer 3

non-polar
e.g. lipids

Question 4

why does water have a high specific heat capacity

Answer 4

• it has many hydrogen bonds
• although they are weak, there are lots of them
• the large number of bonds to break requires a lot of energy / heat
• therefore the heat being transferred to water is used up in breaking the bonds first, before the particles can gain kinetic energy

Question 5

what is the advantage to living organisms for water having a high specific heat capacity

Answer 5

• living organisms have a high specific heat capacity > due to lots of water within the organisms
• this means that a lot of the heat is absorbed by the water without the temperature of it changing too much

Question 6

why is the high specific heat capacity of water an advantage to aquatic organisms

Answer 6

• large bodies of water such as the ocean dont change temperature as quickly or highly as the air
• this provides aquatic organisms with an environment where temp changes are very small and gradual

Question 7

why does water have a high latent heat of vaporisation

Answer 7

• water has a lot of hydrogen bonds which take a lot of energy to break

Question 8

why is a high latent heat of vaporisation advantageous to organisms

Answer 8

• water provides a cooling effect
• humans sweat > water released onto skin > heat from skins surface is transferred to the water (sweat) to evaporate it
• this removes heat from the organisms and therefore cools it down

Question 9

why does water have cohesion

Answer 9

hydrogen bonding between the S- O and S+ H between molecules

Question 10

why is cohesion advantageous to organisms

Answer 10

• supports transpiration in plants > continuous column of water
• surface tension in water > provides organisms with a habitat away from predators with the water

Question 11

why is water classed as a metabolite

Answer 11

• involved in many reactions such as hydrolysis and condensation etc