AS

A2

Biological Properties of Water




File:210 Hydrogen Bonds Between Water Molecules-01.jpg


Water is the only molecule that is absolutely vital for life. It's many unusual properties enable it to carry out specific requirements. Those properties are due to it's polar nature and the way hydrogen bonds form between each water molecule. 













   


Properties of water include;
- It is a liquid at room temperature.
- It's solid has a lower density than it's liquid state.
- It is a good solvent.
- It has cohesion.
- It has a high specific heat capacity. 
- It has a high latent heat of vaporisation. 
- It is a reactant in photosynthesis and hydrolysis.









Water is a liquid at room temperature.

Water is a liquid at room temperature because it has strong hydrogen bonds that make it harder for each molecule to escape and form a gas. It has a low viscosity too, which means it can flow easily.

Because water is a liquid at room temperature and can flow

  • it provides habitats for aquatic animals.
  • forms a major component of tissues and cells. 
  • is an appropriate medium for chemical reactions.
  • It is a good base for effective transport mediums such as blood. 
Solid water is less dense than liquid water.


Water is a good solvent





Cohesion and surface tension




High specific heat capacity

Water needs to take in a lot of heat energy in order to increase its temperature. This means water does not cool down or heat up easily so it's temperature stays quite stable. This is essential for Enzyme reactions to occur in cells and allows aquatic organisms to have a stable environment to live. 


High latent heat of vaporisation.

Water needs a lot of energy to break the hydrogen bonds between the molecules in order for liquid water to become a gas. When water evaporates, each molecule carries away some energy. This allows mammals to be cooled by sweat evaporating and plants to be cooled when water evaporates from mesophyll cells. 







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