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
How does the density of water help other organisms and the environment?
In terms of ice and environment
Because ice is less dense than water:
* Aquatic organisms have a stable environment in which to live through winter
* Ponds and other bodies of watwe are insulated against extreme cold because the layer of ice reduces the heat lossfrom the rest of the pond
What does many of waters properties depend on?
Its polar nature and the hydrogen bonding
How is water molecules different compared to other liquids when they move around in a substance?
They continually make and break hydrogen bonds
Why is water a liquid at room temperature compared to other less polar molecules, which are gasses at room temperature?
eg. H2S
hydrogen bonds between molecules makes is fiddicult for the molecules to escape and become a gas
Cuz of high intermolecular forces, a lot of energy needed to break bonds
How viscous is water?
It has a low viscosity
Why is water being liquid at room temperature good for organisms?
- Provide habitat for living things in rivers, lakes and seas
- Form a major component of the tissues in living organisms
- Provide a reaction medium for chemical reactions
- provides an effective transport medium eg. in blood and vascular tissue
What does cohesion involve?
Intermolecular forces between like molecules
* Which is why water molecules are able to hold themselves together in a drop
Why are watermolecules cohesive?
Theyre very cohesive because of the molecules’ polarity
This is why you can fill a glass of water just barely above the rim without it spilling
What does cohesion mean?
The tendency of water molecules to stick to each other due to hydrogen bonding
How is cohesion good for organisms?
- Cohesion allows water to be pulled up through plant roots and stems to reach the leaves, where it is needed for photosynthesis
How is water a good solven?
because of its polar nature its good for ionic substances
- because the negative and positive part of water is attracted to the positive and negative parts of the solute
How is water made a solvent?
-The water molecules will cluster around these charged parts of the solute and will help to separate them and keep them apart
- At this point they dissolve and a solution is formed
How is water a good solvent fir reactions?
- Molecules and ions can move around and react with each other in water
- Molecules and ions can be transported around living things whilst dissolved in water
Such reactions happen in the cytoplasm of cells is over 70% water
