1.6.3 ~ water Flashcards
how much of a cell is water
75-90% of the mass of a cell
how is water involved in metabolic reactions
it is the medium where metabolic reactions take place in cells
what is water made of
-oxygen molecule
-2 hydrogen atoms
-covalent bonded
polarity of water
-water is a polar molecule
-although water as a whole is electrically neutral, the sharing of electrons between oxygen and hydrogen atoms is unequal
-the oxygen atom attracts the electrons more strongly than the negative hydrogen atoms, resulting in a weak negatively charged region on oxygen atom (δ-) and weak positively charged region on hydrogen atoms (δ+)
-this results in an asymmetrical shape
dipole in water
-separation of charge due to the electrons in covalent bonds being unevenly shared is a dipole
-water molecule has one end that is positively charged and one that is negative so it is a polar molecule
hydrogen bonding in water
-hydrogen bonds form between water molecules as a result of polarity between the positive and negative charges regions of adjacent water molecules
-hydrogen bonds are weak so are contently being broken and reforming. however, there large numbers give a strong structure
6 properties of water
-an excellent solvent
-high specific heat capacity
-high latent heat of vaporisation
-less dense when a solid
-high surface tension and cohesion
-acts a reagent
water as a solvent
-water is a polar molecule so many ions and covalently bonded polar molecules will dissolve in it
-this allows chemical reactions to occur within cells (as the dissolved solutes are more chemically reactive when they are free to move about)
-metabolites can be transported efficiently
specific heat capacity definition
The specific heat capacity of a substance is the amount of thermal energy required to raise the temperature of 1kg or (gram) of that substance by 1°C
waters specific heat capacity
4200 J/kg°C
what does a high specific heat capacity mean
a relatively large amount of energy is needed to raise its temperature
why does water have a high specific heat capacity
many hydrogen bonds, takes a lot of thermal energy to break these bonds and a lot of energy to build them, so temperature of water of water does not fluctuate greatly
advantage of high specific heat capacity of water for habitats
-buffers temperature change
-able to maintain a constant temperature as water is able to absorb a lot of heat without big temperature fluctuations
-this is important for maintaining temperatures for optimum enzyme activity
specific heat capacity of water useful for transferring heat around the body
-water is in blood plasma
-as blood passes through more active regions of the body, heat energy is absorbed but the temperature remains fairly constant
-water in tissue fluid also plays an important role maintaining a constant body temperature
why does water have a high latent heat of vaporisation
-to change sate a large amount of thermal energy must be absorbed by water to break the hydrogen bonds and evaporate