- Created by: alvlrevision
- Created on: 22-11-17 20:29
Water is a polar molecuel (slightly charged).
Water is bonded with both covalent bonds and hydrogen bonds.
> Provides a habitat for living things in lakes, rivers, seas and other bodies of water.
> Forms a major component of tissue.
> Provides a reaction medium for chemical reactions.
> Provides an effective transport medium.
> Ice is less dense than water because by 4 degrees the polar molecules align themselves so they turn into a solid form (ice).
> Because is is less dense than water, aquatic animals ahve a stable habitat during winter and ponds etc are insulated against extreme cold.
> Water is a good solvent
> Because water is polar, the positive and negative parts of the molecule attract to the solute.
> They cluster around the solute molecules keeping them apart.
> Because of this, molecules and ions can be transported around living things whilst dissolved in water.
Property: Cohesion + Surface Tension
> Hydrogen bonding pulling water molecules together is cohesion.
> Surface tension is as a result of hydrogen bonds between molecules of the surface of water and molecules beneath the surface of water.
> The surface of the water contracts as the molecules are being pulled inwards.
> Surface tension = the water thus has the ability to resist force put on it.
Property: High Specific Heat Capacity
> High specific heat capacity = the amount of heat energy required to raise the KE and temperature of molecules.
> 4.2kJ energy is required to raise the temperature of 1kg of water by 1 degree.
> This is important for living things for enzyme-controlled reactions.
Property: Latent Heat of Vaporisation.
> Latent heat of vaporisation helps the molecules to break away from eachother when water evaporates.
> Water is therefore able to help cool living things.
> Water is a reactant in reactions.
> For example: photosynthesis, hydrolysis reactions, digestion of starch, proteins and lipids.