Water

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  • Created by: EClou
  • Created on: 17-04-15 19:34
what is a hydrogen bond
a weak interaction that can occur wherever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen. water molecules hydrogen-bond with each other extensively.
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why is water described as a polar molecule?
water molecules are slightly negatively charged at the O2 end and slightly positively charged at the H+ end because the shared electrons aren't evenly distributed so the O2 pulls some of the shared electrons towards itself and away from the Hs
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why must pure water be heated to 100oC to boil?
in pure water the water molecules create a network allowing them to move around, they continuously make and break H bonds as they move, this makes it harder for for the molecules to 'escape'
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why does it require a large amount of energy to heat water?
because the hydrogen bonds restrict the movement of water molecules
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why is the fact that ice floats on liquid water beneficial to some living organisms?
this means that it insulates the water below and therefore thus allows some organisms to survive the winter and even live below the ice
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how do substances dissolve?
only polar substances can dissolve, the H2O molecules surround the polar ends (interaction), keeping the solute molecules apart - it is dissolved
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is water ideal as a transport medium?
yes
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why is is important that water is liquid over a large range of temperatures?
emperature on the earth and in living organisms (due to living processes) vary, however metabolic processes require water.
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name the cellular processes in moving water (1.) in and (2.) out of cells
1. endopinocytosis and 2. exopinocytosis
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what is the importance of water being a solvent? and give one e.g.
metabolic processes in all cells rely on chemical being able to react together in solution. e.g. 70-95% of cytoplasm = H2O - dissolved chems take part in photosynthesis and respiration
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what is the importance of water being liquid? and give one e.g.
many organisms rely on water as a liquid transport medium for the movement of materials around an organism e.g. blood in animals
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what is the importance of thermal stability? and give one e.g.
large bodies of water are able to to have fairly constant temperatures and evaporation of water cools surf`css by removing heat, e.g. humans sweat - use evaporation as a cooling system
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what is the importance of freezing? and give one e.g.
when water freezes the ice rises and floats on there surface insulating the water below so it is less likely to freeze e.g. lake - the whole lake normally doesn't freeze so aquatic animals are able to live below the ice during winter
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what is the importance of cohesion? and give one e.g.
water molecules stick to each other, this can create surface tension at the surface of the water and also allows water to form long, strong columns that don't easily break e.g. water boatmen skate on the surface of the water in ponds
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what is the importance of water being metabolic? and give one e.g.
water take part as a reactant in some chemical processes e.g. water molecules are used in hydrolysis reactions during photosynthesis
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Card 2

Front

why is water described as a polar molecule?

Back

water molecules are slightly negatively charged at the O2 end and slightly positively charged at the H+ end because the shared electrons aren't evenly distributed so the O2 pulls some of the shared electrons towards itself and away from the Hs

Card 3

Front

why must pure water be heated to 100oC to boil?

Back

Preview of the front of card 3

Card 4

Front

why does it require a large amount of energy to heat water?

Back

Preview of the front of card 4

Card 5

Front

why is the fact that ice floats on liquid water beneficial to some living organisms?

Back

Preview of the front of card 5
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