Water Flashcards
(24 cards)
What are the 5 functions of water?
> Water is a reactant > Water is a solvent > Water transports subtances > Water helps with temperature control > Water is a habitat
Give example of water been a reactant.
Water is a reactant in reaction such as photosyntheses and in hydrolysis reactions such as digestion of starch, proteins and lipids.
how the role of water been a reactant important?
its role as a reactant is important for digestion and synthesis of large molecules
Describe water been a solvent.
water is a solvent, which means more substance dissolve in it.
Advantages of water been a solvent
> Molecules and ions can move around and react together in water - many such reactions happen in the cytoplasm of cells
molecules and ions can be transported around living things whilst dissolved in water
Describe water as transporting subtances
the fact its a liquid and a solvent means it can easily transport all sorts of materials, like glucose and oxygen around plants and animals
Describe water been able to help with temperature control
Because it has a high specific heat capacity and a high latent heat of evaporation
Describe water as a habitat
the fact that it helps with temperature control, is a solvent and become less dense when it freezes means many organism can survive and reproduce
How is water a polar molecule?
because it has a partial negative charge on one side and a partial positive charge on the other
What gives water a high specific heat capacity?
Hydrogen bonds as the bonds between water molecules can absorb a lot of energy
What does water having a high specific heat capacity mean
it means water takes a lot of energy to heat it therefore it doesn’t experience rapid temperature change
Definition of specific heat capacity
this is the temperature needed to raise the temperature of 1G of a substances by 1DC
Advantage of liquid been at room temperature
> Provide habitats for living thing in rivers, lakes and seas
Form a major component of the tissues in living organism
Provide a reaction medium for chemical reactions
Why does water have high latent heat of evaporation ?
because hydrogen bonds take a lot of energy to break
Definition of high latent heat of evaporation
a lot of energy is used up when water evaporates ( changes from a liquid to a gas)
Advantage of water having a high latent heat of evaporation
its useful for living organisms because it means water’s great for cooling things e.g. mammals are cooled when sweat evaporates
What is cohesion?
its the attraction between molecules of the same type
Describe water molecules as been cohesive
they are very cohesive ( they tend to stick together) because they’re polar
Pro of water been cohesive
it helps water to flow making it great for transporting substances e.g. helps water to be transported up plant stems in the transpiration system
What is surface tension?
all water molecules are hydrogen bonded to the one beneath them, hence more attracted to the one beneath than to the air molecules. this means the surface of the water contracts and gives the surface an ability to resist force applied to it
pros of water having surface tension
Insects like pond - skaters can walk on water
what makes ice less dense than water
water molecules are held further apart in ice than they are in liquid water because each water molecules forms four hydrogen bonds to other water molecules making it a lattice
Pros of ice been less denser than water
> aquatic organisms have a stable environment in which to live through the winter
ice forms an insulating layer on top of water
What is a hydrogen bond?
a weak bond between a slightly positively charged hydrogen atom in one molecule and a slightly negatively charged atom in another molecule
