Water

what is water a major part of?

major component of cells

structure of water

- dipolar- O slightly negative, H slightly positive

- attractive force between these opposite charges is a hydrogen bond

what causes the unique properties of water

the hydrogen bonds which are individually weak but together are strong causing the water molecules to stick together

what are the 5 key properties of water?

1. high specific heat capacity

2. large latent heat of vaporisation

3. strong cohesion

importance in loving organisms as :

1. metabolite

2. solvent

specific heat capacity of water

- need alot of energy to raise temperature due to strong hydrogen bonds

- gain/lose a lot of heat/energy without changing temperatures

- useful to organisms as it means temperature remains stable even if surrounding temperature fluctuates significantly

latent heat of vaporisation of water

- need alot of energy to evaporate 1 gram of water due to hydrogen bonding

- means water has a significant cooling effect

What causes the large cohesive forces in water?

Hydrogen bonding

What allows water to be pulled up through a tube, such as a xylem vessel in plants?

Cohesive forces due to hydrogen bonding

What happens when water molecules meet air?

They tend to be pulled back into the body of water rather than escaping- surface tension

surface tension in water

It means that the water surface acts like a skin and is strong enough to support small organisms.

What is an example of a small organism that can be supported by water's surface tension?

Pond skaters

what is cohesion

The tendency of molecules to stick together

water as a metabolite

- involved in many reactions, e.g. photosynthesis, hydrolysis

- chemical reactions take place in an aqueous medium

- why 90% of plasma in blood/ cytoplasm is largely composed of water

water as a solvent

The universal solvent!

- Polar or charged molecules dissolve readily in water as its dipolar (hydrophilic), non-polar molecules cannot dissolve (hydrophobic)