The Properties of Water
- Created by: iloverevision:)
- Created on: 01-03-19 18:08
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- Properties of Water
- Specific Heat Capacity
- water molecules stick together by hydrogen bonding
- takes lots of energy to separate them
- this is why water has higher boiling point than predicted
- presence of hydrogen bonds mean that water has highest specific heat capacity
- amount of energy needed to change temperature of 1kg of substance by 1 degrees
- SHC of pure water is 4910
- water molecules stick together by hydrogen bonding
- Latent Heat of Vapourisation
- when substance turns from liquids to gas it requires energy
- potential energy stored in forces between molecules need to be overcome by kinetic energy of motion of particles before it changes phase
- high degree of hydrogen bonding between molecules means lots of energy is required to evaporate 1g of water
- LHoV
- water has large LHoV
- explains why sweating cools body
- body rises above normal temp, sweat is secreted
- water molecules in sweat gain energy
- break free from bonds & become water vapour
- as water evaporates heat energy removed from skin
- loss of energy cools skin
- as water evaporates heat energy removed from skin
- as water has high LHoV lots of heat energy
- break free from bonds & become water vapour
- Cohesion
- tendency of molecules to stick together
- hydrogen bonds mean water has large cohesive forces
- allows to be pulled through tube
- e.g. xylem, straw, pipette
- Surface Tension
- where water meets air the water molecules tend to be pulled back in to body of water
- means water acts like a skin & is strong enough to support small organisms on surface
- where water meets air the water molecules tend to be pulled back in to body of water
- Water as a Solvent
- solvent - liquid which dissolves solute
- solute - substance dissolves in solvent
- water is medium in which enzyme-catalysed reactions take place
- readily dissolves substances
- respiratory gases
- oxygen & CO2
- excretory products
- ammonia & urea
- inorganic ions
- hydrogen & iron
- small hydrophilic ions
- amino acids & ATP
- respiratory gases
- Water in Metabolism
- water used in hydrolysis reactions to break down complex molecules
- protein --> amino acids
- formed in condensations reactions
- starch & protein synthesis
- raw material required in photosynthesis & a product of respiration
- water used in hydrolysis reactions to break down complex molecules
- Specific Heat Capacity
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