Water

Question 1

what takes place in water?

Answer 1

all metabolic reactions

Question 2

what is water composed of?

Answer 2

one atom of oxygen combines with two atoms of hydrogen sharing electrons
- covalent bonding

Question 3

why is a dipole created in water?

Answer 3

although water is electrically neutral the sharing of the electrons is uneven between the oxygen and hydrogen atoms

• the oxygen atom attracts the electrons more strongly than the hydrogen atoms,
  resulting in
  a weak negatively charged region on the oxygen ( delta -)
  and a weak positively charge region on the hydrogen ( delta +)
  this results in an asymmetrical shape

Question 4

what is a dipole?

Answer 4

the separation of charge due to the electrons in the covalent bonds being unevenly shared

Question 5

what are the reasons for a molecule to be polar?

Answer 5

one end that is negatively charged

one end that is positively charged

Question 6

where do hydrogen bonds for in water?

Answer 6

hydrogen bonds form between water molecules
- as a result of the polarity of water hydrogen bonds form between the positive and negatively charged regions of adjacent water molecules

Question 7

where do hydrogen bonds for in water?

Answer 7

hydrogen bonds form between water molecules
- as a result of the polarity of water hydrogen bonds form between the positive and negatively charged regions of adjacent water molecules

Question 8

what are the important properties of water?

Answer 8

• and excellent solvent- many substances can dissolve in water
• a relatively high specific heat capacity
• a relatively high latent heat of vaporisation
• water is less dense when a solid
• water has a high surface tension and cohesion
• it acts as a reagent
• good metabolite

Question 9

which two properties of water enable it to have many essential roles?

Answer 9

• the polarity of water molecules
• the presence and number of hydrogen bonds between water molecules

Question 10

what is the specific heat capacity of a substance?

Answer 10

the amount of thermal energy required to raise the temperature of 1kg of that substance to 1°C

Question 11

what is water’a specific heat capacity?

Answer 11

4200 J/kg°C

Question 12

why does water have such a high specific heat capacity?

Answer 12

due to the many hydrogen bonds

it takes a lot of thermal energy to break these bonds, and not a lot of energy to build them
- hence the temperature of water does not fluctuate greatly

Question 13

what is the advantage of the high specific heat capacity of water for living organisms?

Answer 13

Provides suitable habitats

•is able to maintain a constant temperature as water is able to absorb a lot of heat without big temperature fluctuations
- this is viral in miami taint temperatures that are optimal for enzyme activity

•water in blood plasma is also vital in transferring gear around the body, helping maintain a fairly constant temperature

as blood passes through more active (“warmer”) regions of the body, heat energy is absorbed but the temperature remains fairly constant

water in tissue fluid also plays an important regulatory role in maintaining a constant body temperature

Question 14

Latent heat of vaporisation - water - advantages

Answer 14

in order to change state from liquid to gas, a large amount of thermal energy must be aerobes by water to break the hydrogen bonds and evaporate

this is an advantage for living organisms as only a little water is required to evaporate for the organism to lose a great amount of heat

this provides a cooling effect for living organisms

Question 15

cohesion in water

Answer 15

hydrogen bonds between water molecules allow for strong cohesion between water molecules

Question 16

adhesion in water

Answer 16

water is also able to hydrogen bond to other molecules, such as cellulose,