Module 2 Section 2 - Water Flashcards
Why is water important
- it is a reactant and solvent
- it transport substances
- it helps with temperature control
- it is a habitat
What is meant by water is a reactant
It is important in loads of chemical reactions, including hydrolysis reactions
What is meant by water is a solvent
Substances can dissolve in it. Most biological reactions take place in solution
What is meant by water transport substances
It is a liquid and a solvent meaning it can easily transport all sorts of materials like glucose and oxygen around plants and animals
What is meant by water helps with temperature control
Has a high specific heat capacity and a high latent heat of evaporation
What is meant by water is a habitat
many organisms can survive and reproduce in it because, it helps with temperature control, is a solvent and is less dense when it freezes
A molecule of water is….
One atom of oxygen joined by 2 atoms of hydrogen - joined by shared electrons
Why is the other side of each hydrogen left with a slight charge
Because the shared negative hydrogen electrons are pulled towards the one oxygen atom
Why is the oxygen atom slightly charged
Because the unshared negative electrons give it a slight charge
Is water a polar molecule
Yes - it has a partial negative charge on one side and a partial positive charge on the other
What is meant by hydrogen bonding
The slightly negatively charged oxygen atoms attract the slightly positive charged hydrogen atoms of the other water molecules
What is specific heat capacity
The amount of energy needed to raise the temperature of 1 gram of a substance by 1°c
Why do hydrogen bonds allow water to have high Specific heat capacity
The hydrogen bonds between the water molecules can absorb a lot of energy
Because water has a high SHC (Specific Heat Capacity) it means water doesn’t experience what
It means water doesn’t experience rapid temperature changes - this also makes it a good habitat because the temperature under water is likely to be more stable than it is on land
What also does hydrogen bonds give water what
A high latent heat of evaporation
What does high latent heat of evaporation mean
It takes a lot of energy to break hydrogen bonds between water molecules so a lot of energy is used up when water evaporates
What does high latent of evaporation mean for water
Means water is great for cooling things down e.g. we sweat when we too hot when sweat evaporates it cools the surface of our skin
What does water’s polarity make it
Very cohesive
What is cohesion
The attraction between molecules of the same type - water molecules are cohesive because they are polar
What does water’s cohesiveness mean for the properties of water
The cohesiveness means it helps water flow making it great for transporting substances
What does waters polarity also make it
A good solvent
A lot of important substances in biological reactions are ….
Ionic
What does ionic mean
They’re made from one positively charged atom or molecule and one negatively charged atom or molecule
How is water ionic
Because water is polar, the slightly positively charged end of a water molecule will be attracted to the negative ion and the slightly negative end of a water molecule will be attracted to the positive ion
Why will water dissolve other substances
Because the ions will totally get surrounded by water molecules
Water is what when it is a solid
Less dense
What happens to water at low temperatures
It freezes
What does freezing mean for the water molecules
Water molecules are held further apart in ice than they are in liquid water because each water molecule forms 4 hydrogen bonds to other water molecules making a lattice shape
Why is water as a solid beneficial for organisms such as fish
In cold temperatures ice forms an insulating layer on top of water - the water below the ice doesn’t freeze. Meaning fish don’t freeze and can still move around
