1.7- Water Flashcards
1) What does it mean to say that water is a ‘metabolite’?
It means that water is either a reactant or a product of chemical reactions in living organisms
E.g. it is required for hydrolysis reactions to take place and it is produced in condensation reactions
1) What is a solvent? Why can water act as a solvent? How is this beneficial in terms of chemical reactions?
- A solvent is a substance that other substance can dissolve into
- Water is polar, so it can form hydrogen bonds
• This means that polar and ionic substances are able to dissolve in water
• (due to the attraction of opposite charges allowing them to be completely surrounded by the polar water molecules).
This is useful because many metabolic reactions occur when substances are dissolved in water.
1) Explain why there is surface tension in water
Because water molecules are polar, so can form H-bonds with other water molecules.
This causes cohesion between water molecules, holding them together.
(this allows pond skater to walk on water without falling in!)
1) Explain how the properties of water help water to move up the xylem vessel of a plant
- Water is polar so it can form hydrogen bonds between molecules
- Therefore there is COHESION between water molecules (due to H-bonds)
- There is also ADHESION between the water molecules and the wall of the xylem
- Therefore the column of water molecules in the xylem does not break
(i) What does it mean that water has a high specific heat capacity?
High specific heat capacity means that a lot of energy is required to raise the temperature of water
) Why does water have a high specific heat capacity?
(i) Because there are lots of Hydrogen bonds between water molecules and they can absorb lots of energy.
(iii) How is this property beneficial
(i) This makes it good at BUFFERING CHANGES OF TEMPERATURE.
1) (iv) How is it useful to a) aquatic organisms b) humans?
(i) (a) it makes water a good habitat because the temperature underwater is likely to be more stable than on land (so the temperature changes are not as big)
(b) Water INSIDE organisms remains at a fairly stable temperature therefore helping to maintain a constant internal body temperature.
(i) What does it mean when we say that ‘Water has a large latent heat of vaporization’?
(i) This means a lot of energy is required to convert liquid water into water vapour
1) (ii) How is this property beneficial to organisms living in hot countries?
(i) It allows water to provide a cooling effect with little loss of water through evaporation.
This is because it takes a lot of energy to break the hydrogen bonds between the water molecules for evaporation to take place.
This is why organisms sweat or cover themselves in mud!
