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9 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Structure of Water |
●Small dipolar molecule made up of 2 hydrogen atoms covalently bonded to 1 oxygen atom ●The electrons in water are not shared evenly between hydrogen and oxygen ●Large Oxygen pulls electron close towards it to become delta negative And the hydrogen be omes delta positive ●Slight charges attract 1 another to form a weak interaction called a hydrogen bond. These are continually broken and reformed |
Many Hydrogen bonds in water make it a polar molecule |
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Metabolic Role |
●Condensation and Hydrolysis reactions involve water such as joining amino acids or splitting disaccharides |
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High Latent heat of vaporisation |
●Due to many hydrogen bonds it requires a lot of energy to evaporate water. ●Water evaporates from a surface it 'removes' heat and has a cooling effect E.g. SWEATING & TRANSPIRATION |
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High boiling point |
●Continuous making and breaking of hydrogen bonds in water means it is a liquid not gas ●Difficult for water molecules to escape liquid which means it has a high boiling point compared to other similar sized molecules |
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Low Density of Ice |
●As water is cooled,molecules slow down to form more H bonds to firm a crystalline structure which is less dense than liquid water. ●This means that ice floats on water and insulates organisms beneath it |
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High Specific Heat capacity-Thermostability |
●H bonds in water prevent the movement of water molecules so large amounts of energy Is needed to increase temp ●Therefore has a high specific heat capacity ●large bodies of water are thermostable during large external fluctuations of temperature. |
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Cohesion |
●H bonds cause water molecules to stick together ●results in surface tension at surface of water ●allows organisms to walk on water E.g. pond skaters ●●Water can be transported up the xylem in the transpiration stream as cohesion between molecules make long thin columns of water difficult to break |
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Solvent |
●polar makes water really good solvent ●any polar mols like ions will dissolve well ●Negative ions will be attracted to positive end of water and VICE VERSA ●Water mols cluster around charged parts of solute;allows metabolic reactions like photosynthesis and respiration to take place in solution in cytoplasm |
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Transport Medium |
●Water is a good solvent and remains liquid over wide range of temp means water is a good transport medium ●plasma in blood Mineral ions in xylem |
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