Properties of Water
Teacher recommended
?- Created by: SYusuf
- Created on: 26-10-15 16:19
View mindmap
- Water
- Latent Heat of Vaporisation
- The energy required to transform a given quantity of water from a liquid to a gas.
- Because the molecules are held together by hydrogen bonds a lot of energy is needed to of water molecules to evaporate
- Therefore water is useful to cool down living organisms to maintain homoeostasis
- Plants are cooled when water evaporates from mesophyll cells in transpiration
- Humans sweat to cool down their body temperature
- Therefore water is useful to cool down living organisms to maintain homoeostasis
- Because the molecules are held together by hydrogen bonds a lot of energy is needed to of water molecules to evaporate
- The energy required to transform a given quantity of water from a liquid to a gas.
- Liquid
- Hydrogen bonds are constantly broken and remade when water molecules move in liquid.
- These bonds make it difficult for the molecules to escape as gas. Other molecules of similar size (such as H2S) are gas at room temperature.
- Because water is liquid at room temperature it is able to:
- Provide a medium for chemical reactions
- Form a major component of living tissues
- Provide a medium for transport e.g in blood plasma
- Provide a habitat, e.g. in rivers, lakes and seas.
- Because water is liquid at room temperature it is able to:
- These bonds make it difficult for the molecules to escape as gas. Other molecules of similar size (such as H2S) are gas at room temperature.
- Hydrogen bonds are constantly broken and remade when water molecules move in liquid.
- Density
- The density of water is perfect for aquatic organisms to be able to float.
- Unlike most liquids which become more dense when they cool, water becomes less dense between 4-0 degrees. This allows ice to float on top of water.
- Aquatic animals have a stable environment to live in the winter (under and atop the layer of ice)
- Bodies of water are insulated against extreme cold by a layer of ice which reduces the rate of heat loss.
- Solvent
- Water is a good solvent for ionic molecules and covalent molecules.
- Because water is polar it is attracted to the slightly charged parts of the solutes. They cluster around these charged parts and will separate them and keep them apart.
- This helps molecules and ions move around and react together in water e.g in the cytoplasm
- This also helps molecules and ions to be transported around the body while dissolved in water/
- Because water is polar it is attracted to the slightly charged parts of the solutes. They cluster around these charged parts and will separate them and keep them apart.
- Water is a good solvent for ionic molecules and covalent molecules.
- Cohesion & Surface Tension
- Hydrogen bonding pulls water molecules together
- This causes them to stick together (cohere) instead of spreading out
- This also means that water contracts as molecules on the surface are pulled inwards by hydrogen bonds to molecules beneath.
- This means water is able to resist force applied to it, this property is known as surface tension.
- This allows:
- Columns of water in plant vascular tissue to be pulled up the xylem together from the roots.
- Insects like pond skaters to walk on water.
- This allows:
- This means water is able to resist force applied to it, this property is known as surface tension.
- Hydrogen bonding pulls water molecules together
- Specific Heat Capacity
- The amount of energy needed to raise the temperature of 1 kg of water by 1 degree celcius.
- Due to hydrogen bonds water has a high SHC of 4.2 kJ. This means it does not heat up or cool down easily
- Because the main component of living organisms is water this makes it easier to maintain a constant temperature needed for enzyme controlled reactions.
- Due to hydrogen bonds water has a high SHC of 4.2 kJ. This means it does not heat up or cool down easily
- The amount of energy needed to raise the temperature of 1 kg of water by 1 degree celcius.
- Reactant
- Water is important for the digestion of large biological molecules (such as starch, proteins and lipids) through hydrolysis.
- Water is a reactant in photosynthesis which is important for the synthesis of glucose
- Latent Heat of Vaporisation
- A lot of water's properties are due to its polar nature, which allows for the formation of hydrogen bonds
Comments
Report