Water - functions and properties.
- Created by: emx11
- Created on: 23-01-16 15:32
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- Water
- A dipole
- A polar molecule with a positive and negative charge, separated by a very small distance.
- No overall charge
- Hydrogen Bonds
- The weak attractive force between a ?+ hydrogen atom of one molecule and a ?- oxygen atom on another.
- Essential properties for life as we know it.
- A solvent
- Chemical reactions take place in solution. Transport medium eg. animal plasma and xylem and poem in plants.
- As a metabolite
- Reactant in many biochemical reactions e.g. with carbon dioxide to produce glucose.
- Hydrolysis e.g. - maltose + water = glucose + glucose.
- Condensation.e.g. glucose + fructose = sucrose + water
- High specific heat capacity
- A large amount of heat energy is needed to raise the temperature. Prevents large fluctuations in water temperature, important in stability of aquatic environments.
- High latent heat of vaporisation
- A lot of energy required to change state from liquid to a vapour. Important in temperature control.
- Cohesion
- Water can be drawn up in columns via xylem vessels due to H-bonds.
- High surface tension
- At ordinary temperatures water has the highest liquid tension (apart from mercury). Supports insect bodies e.g. pond skater.
- High density
- Denser than air, provides support for aquatic organisms. Maximum density 4C.
- Ice less dense than water so floats, proving a good insulator. Organisms beneath can survive.
- Transparent
- Allows light to pass through and for photo synthesis
- A solvent
- A dipole
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