Essentials 4 Life- Water Flashcards
Water as a solvent
Because water is charged, it is a very good solvent. Charge and polar molecules such as salts,sugars,amino acids dissolve readily in water so are therefore hydrophilic. Whereas uncharged and non-polar molecules such as lipids are not dissolvable in water so are therefore hydrophobic.
Specific heat capacity
Water has a specific heat capacity of 4.2 j g-1 degrees c-1, which means that it takes 4.2 joules to heat up 1g of water by 1 degree Celsius . This is unusually high and means that water does not change temperature easily. This minimises fluctuations of temperature inside cells, and makes se temperature stay remarkably constant
Latent heat of vapourisation
Water requires a lot of energy to change its state from liquid to gas, and this is made us of as a cooling mechanism in animals ( sweating and panting) and plants ( transpiration) . When water evaporates it extracts heat from around it, cooling organisms
Latent heat of fusion
Water requires a lot of energy to change state from solid to liquid and must lose a lot of energy to change state from liquid to solid. This makes it difficult for water to freeze, meaning its less likely to form ice crystals inside of the cells
Density
Water is unique in that at its solid state (ice) it is less dense than at its liquid state. As the air temperature cools, the bodies of water freeze from its surface. This means that it forms a layer of ice on the surface of the water, leaving liquid water beneath, thus acting as a insulator for the aquatic ecosystems. This allows them to live in sub-zero temperatures
Cohesion
Water molecules are bonded together by hydrogen bonds , making water highly cohesive. This explains why water can be sucked up long columns such as trees in transpiration without breaking. This also explains water tension in the reason as to why some insects can stand or walk on water
