Properties of water Flashcards
What are all the 8 properties of water?
Liquid at room temperature
Density
Good solvent
Cohesion and surface tension
Adhesion?
High specific heat capacity
High latent heat of vaporisation
A reactant
Why is water liquid at room temperature?
Why?
Because of the strong hydrogen bonding between water molecules
It takes a lot of energy to increase the temperature of water molecules so it turns into a gas (evaporates)
Fix denne
What is water temperature a measure of ?
The kinetic energy of the water molecules
(Therefore you have to put in a lot of heat energy to raise the temperature and their kinetic energy)
What is the amount of heat energy needed to raise the temperature know as?
The specific heat capacity
What is the advantage of the specific heat capacity for water?
- Water does not heat up or cool down easily
- Living things, including prokaryotes and eukaryotes, need a stable temperature for enzyme controlled reactions to take place
_ Aquatic organisms need a stable environment in which to live
(because the main comonent of many living things is water, and many organisms live in water, its high specific heat capacity is important to maintain stability)
What is the difference between latent heat of vaporisation and Specific heat capacity?
SHC= amount of energy needed to raise one kilogram of a substance by 1 C
Latent heat of vaporisation= amount of energy needed to change the state of a substance from liquid to gas without changing the temperature
SHC is for change in temperature while LHV is for a change in state
What is latent heat of vaporisation?
Its heat energy known as latent heat that helps molecules break away from each other to become a gas
Is it easy for a change of state from liquid to gas?
Why not?
It is not easy because the molecules are held together by hydrogen bonds, so a relatively large amount of energy is needed for water molecules to evaporate
Why is the vaporisation of water so important for life?
Because water evaporating helps cool living things to maintain a stable temperature.
What are examples to the importance of water evaporating for organisms?
LHV
e.g. mammals are cooled down when sweat evaporates
plants are cooled when water evaporates from mesophyll cells
What processes are water used as a reactant?
Photosynthesis
hydrolysis reactions
e.g. digestion of starch, proteins and lipids
What is water’s role as a reactant extremely important for?
Digestion and synthesis of large biological molecules
Why does the density of water provide the ideal habitat for living things?
Because it allows aquatic animals to float, if it was less dense than it is now it would be very difficult for those organisms to float
How is water different from most liquids?
what would happen if that were the case?
in terms of density
Because liquids become more dense as it gets colder
- if this was the case, the water at the top of the pond would freeze and sink and then the water replacing it at the top would freeze and sink too until the pond becomes full of ice
How does water behave differently in terms of it freezing?
It becomes more dense as it becomes colder until about 4 C.
From 4 C to freezing point, the water molecules align themselves in a structure which is less dense than a liquid
( this is because of its polar nature)
Usually liquids are not in a specific structure which is why the ice would then be less dense as its arranged in a structure
