3.1.7 Water Flashcards
1
Q
what does polar mean?
A
slightly charged, doesn’t lose/gain electrons - they’re distributed unequally. it’s not an ion. water is polar
2
Q
what are the 5 key properties of water?
A
- is a metabolite
- is an important solvent
- has a relatively high heat capacity
- has a relatively large heat latent of vaporisation
- cohesion
3
Q
why is water a metabolite?
A
used up in many reactions e.g in photosynthesis and hydrolysis
4
Q
why does water have a relatively high heat capacity?
A
- large amount of energy needed to raise the temperature of water to break the hydrogen bonds
- useful for living organisms because it means that water doesn’t experience rapid temperature changes (buffering changes in temperature)
- good habitat because temperature under water is likely to be more stable than on land
5
Q
why does water have a relatively large latent heat of vaporisation?
A
- a lot of energy is needed to break the hydrogen bonds to change state of water to vapour
- cooling effect with little loss of water through evaporation
- water evaporates and carries away heat energy from the surface and helps lower the temperature
6
Q
why is it an important solvent?
A
- waste/excretory materials are able to dissolve
- diluting affect - reducing the toxicity of excretory materials
- breaks down + dissolves food molecules in animals
- blood plasma is 92% water
7
Q
how is water cohesive?
A
- between water molecules - supports columns of water in the tube-like transport cells of plants e.g. xylem
- helps water to flow
- strong cohesion also means high surface tension when it comes into contact with air
8
Q
what does cohesive mean?
A
attraction between molecules of the same type like two water molecules
