Water Flashcards
what is a hydrogen bond
a weak interaction that occurs when molecules contain a slightly negatively charged atom bonded to a slightly positively charged atom
which bonds are hydrogen bonds weaker than
covalent bonds
how many hydrogen bonds form in polymers
thousands and thousands
how is having many hydrogen bonds beneficial
it helps stablisise the structure of some biological molecules
what atoms do water consist of
two hydrogen atoms covalently bonded to one oxygen atom
why is the oxygen atom slightly negative
oxygen atoms have a greater number of positive protons in its nucleus which exerts a stronger attraction for shared electrons
if oxygen is slightly negative, what does that make hydrogen
slightly positive
what type of molecule is water
polar molecule
what is specific heat capacity
the amount of energy required to raise one kg of a material by 1 degrees celsius
what is specific latent heat
the amount of energy required to change the state of one kg of a material without changing its temperature
what are the functions of water
- it is a good solvent
- reactant
- can make a good habitat
- controls temperature
- transport medium
describe the polarity of water
shared electrons of covalent bond are more strongly attracted to the oxygen atom which makes the molecule have a slight negative charge on the oxygen atom and a slight positive charge on the hydrogen atom
what can interact with water as a result of its polarity
other polarised molecules can interact with water and dissolve. this also includes ionic solutes
how do substances dissolve in water
because water is polar, positive and negative parts of the water molecule are attracted to the negative and positive parts of the solute. water molecules cluster around these charged parts of the solute molecules and will help separate them and keep them apart. they dissolve to form a solution.
are hydroxyls (-OH) polar or non polar
polar
where do non polar solutes dissolve in
non polar solvents
how is water being a good solvent beneficial for organisms
- molecules and ions can move around and react together in water. many such reactions happen in cytoplasm as it is 70% water.
- molecules and ions can be transported around living things whilst being dissolved in water
why does ice float on water
in a liquid state, water molecules are closely held together by weak hydrogen bonds. on reaching a solid state, hydrogen bonds become stable arraning water molecules far apart from each other. this causes ice to have lesser density than water so it floats
how is ice less denser than water
water becomes less dense when frozen but becomes more dense as it gets colder until about 4 degrees. as it goes from 4 degrees to freezing point, water molecules align themselves in a structure which is less dense than water
how does the density of water provide an ideal habitat for living things
- aquatic organism have a stable environment in which to live throughout the winter.
- ponds and other bodies of water are insulated against extreme cold.
- the layer of ice reduces the rate of heat loss from the rest of the pond which insulates the water beneath
what happens when water molecules constantly move around
they continually move and break hydrogen bonds
what do the hydrogen bonds make difficult for the water molecules
for them to escape and become a gas
does water have a high or low viscosity
low viscosity (flows very easily)
what can water provide because of its viscosity
- it provides habitats
-form major componenet of tissues in living organisms,
-provide reaction medium for chemical reactions, - provide a transport medium
how is water adhesive
it has a tendency for the water molecules to stick to other substances
how is water cohesive
it has a tendency for water molecules to stick to each other
why is water cohesive
the hydrogen bonds between the molecules pulls them together
where else does cohesion happen
at the surface of the water. water molecules at the surface are all hydrogen bonded to molecules beneath. they are more attracted to water molecules beneath than to air molecules above. this causes the surface of water to contract (molecules are pulled inwards)
what is surface tension
the surface of water has the ability to resist force applied to it.
what are the advantages of cohesion, adhesion and surface tension
- columns of water in plant vascular tissue are pulled up the xylem tissue from the roots
- insects such as pond skaters can walk on water
does water have a high or low specific heat capacity
high specific heat capacity
how many joules of energy are required to raise 1kg of water by 1 degrees Celsius
4200J
why does water have a high specific heat capacity
water temperature is a measure of the kinetic energy of water molecules. water molecules are held together quite tightly by hydrogen bonds so you have to put a lot of heat energy to increase the kinetic energy and therefore the temperature
what is the advantage of water having a high shc
water doesnt fluctuate in temperature which makes it stable for living things. it is good for enzyme controlled reactions and creates a stable environment for aquatic organism
why is water considered to be a coolant
because of its high latent heat of vaporisation, water cools living things and keeps the temperature stable
why does water have a high specific latent heat of vaporisation
molecules of water are held together by hydrogen bonds so a large amount of energy is needed for water molecules to evaporate
why is water being a reactant important
it is important for the digestion and synthesis of large biological molecules
