water

Question 1

Water is described as a polar molecule. Define the term polar and describe how this property manifests in the structure of a water molecule

Answer 1

The uneven spread of electronic charge between oxygen and hydrogen; [1 mark]
Electrons are more strongly attracted towards oxygen [1 mark]
This causes an asymmetrical molecular shape / 105° bond angle; [1 mark]

Question 2

Astronomers lookingfor evidence of life on other planets and moons often look for signs of water existing or having existed on those bodies,.Use your knowledge of the properties of water to explain why watyer can provide evidence for life (3 marks )

Answer 2

Water is polar and is a universal solvent/medium for biological reactions / method of transport for dissolved solutes; [1 mark]
water can create stable habitats [1 mark]
Ice floats on liquid water which allows life to thrive under the ice cap; [1 mark]
Water has high surface tension that allows small organisms to populate the surface;
[1 mark]

Question 3

What are the properties of water

Answer 3

*A metabolite in condensation/hydrolysis/ photosynthesis/respiration;
2. A solvent so (metabolic) reactions can occur or allowing transport of substances;
3. High (specific) heat capacity so buffers changes in temperature;
4. Large latent heat of vaporisation so provides a cooling effect (through
evaporation);- So helps organisms maintain a constant internal body temperature

5. Cohesion (between water molecules) so supports columns of water (in plants);

Question 4

What is meant by high heat capcity and how does it act as a buffer

Answer 4

*water is able to absorb heat without change in temp due to it requiring lot of enrgy to raise to 1 degree
*acts as buffer as absorbs heat as minimizes temp fluctuations and provides stable environment

Question 5

What does buffer mean

Answer 5

something that minimizes/ resists changes in a particular condition.

Question 6

What is meant by large latent heat of vaporisation and how it provides a cooling effect

Answer 6

+takes a lot of energy to change water from a liquid to a gas (vapor). because of the strong hydrogen bonds between water molecules, which require significant energy to break.

Cooling Effect: When water evaporates , it removes a lot of heat from the body, helping with temperature regulation.