Water Flashcards
What is the structure of water?
two hydrogen atoms and one oxygen atom covalently bonded together
what type of molecule is water?
it is a dipolar molecule
what does dipolar mean?
pair of equal and opposite electric charges
what is hydrogen bonding?
electrostatic forces of attraction between positive pole of a water molecule with negative pole of another
name properties and uses of water
- temperature control:
- specific heat capacity
- latent heat of vaporisation
- cohesion - transport
- solvent
- surface tension - support
- metabolite
what is specific heat capacity?
energy required to raise the temperature of 1g of a substance by 1 degree Celsius
does water have high or low specific heat capacity?
high
- absorbs lots of heat before temperature changes
why is the property of specific heat capacity important in animals?
- water acts as a buffer to sudden temperature changes
give another reason why animals can survive at bottom of pond when covered in ice
- ice is an insulator
- less dense than water because particles held further apart in lattice so can float on top
- prevents heat loss
what is latent heat of vaporisation?
heat energy required to transform water to a vapour
does water have high or low latent heat of vaporisation?
high
- lots of heat needed to change water into vapour
what do mammals produce to release heat?
produce sweat
- evaporation of sweat cools body by taking heat away from body
what is cohesion?
tendency of molecules to stick together
why is water cohesive?
due to hydrogen bonding - attraction of poles - flow as one unit
why is cohesion a useful property of water?
- useful for transport
- allows water to be drawn up by xylem vessels
why is water a good solvent?
readily dissolves substances due to its polarity
how is sodium chloride dissolved in water?
tiny charges on water molecules attract ions so they can spread through the water
what types of substances can water dissolve?
- gases - oxygen/carbon dioxide
- waste - ammonia/ urea
- inorganic ions - sodium/ phosphate/ iron/ hydrogen
- small hydrophilic molecules
- enzymes
what is surface tension?
when water interacts with air, molecules tend to pull back due to hydrogen bonds rather than escape so acts like a skin and strong enough to support small organisms
what is a metabolite?
substance involved in a metabolic reaction
what is a metabolic reaction?
a chemical reaction that happens to keep an organism alive
name examples of metabolic reactions that water is involved in
- hydrolysis
- condensation reactions
- photosynthesis
why is useful that water is transparent?
- plants photosynthesise easily
- light rays penetrate eye fluid to reach retina
why is water good for support in plant cells
not easily compressed so makes cell turgid
