Functions of water:
- A reactant in many important chemical reactions- like photosynthesis and hydrolysis
- A solvent which means that substances can dissolve in it
- Transports substances, because it is a solvent. Substances such as water and glucose
- Helps with temperature control. Carries heat energy away when it evaporates, which helps to cool
Structure of water molecules
- Shared negative hydrogen electrons are pulled towards oxygen, the other side of each hydrogen atom is left with a slight positive charge
- Unshared negative electrons on the oxygen atom give it a slight negative charge.
- Makes water a polar molecule
- Negatively charged atoms of water attract the positively charged hydrogen atoms or other water molecules. This is called hydrogen bonding
Structure related to its properties & functions
- Specific heat capacity- Is the energy required to raise the temperature of 1g of a substance by 1 degree. Hydrogen bonds between water molecules can absorb a lot of energy, so water has a high specific heat capacity. Takes a lot of energy to heat it up. Useful for living organisms because it stops rapid temperature changes, allowing them to keep temperature fairly stable
- High latent heat of evaporation- Takes a lot of energy to break hydrogen bonds between molecules, so a lot of energy is used up when water evaporates. Useful because it allows organisms to cool down quickly
- Water's polarity makes it very cohesive- Water molecules are cohesive which allows it to flow and also to transport substances
- Water's polarity makes it a good solvent- Because its polar, the positive end of a water molecule will be attracted to the negative ion, and the negative end of a water molecule will be attracted to the positive ion. So they will dissolve
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