3.1.8 Water

Question 1

Describe the structure and bonding present in water.

Answer 1

1. Water is a covalent compound made up of 2 hydrogen atoms + 1 oxygen.
2. Oxygen has a slight negative charge and hydrogen atoms have a slight positive charge = (di)polar.
3. Hydrogen bonds (attractive force between opposite charges) form between water molecules causing them to ‘stick together’.

Question 2

Cohesion:

Answer 2

1. Water is a polar molecule. Hydrogen bonds form between molecules so water molecules tend to stick together.
2. Column of water doesn’t break when pulled up a narrow tube, xylem during transpiration.
3. Produces surface tension at an air-water surface so pond skaters can walk on water.

Question 3

Metabolite:

Answer 3

1. Water is reactive.
2. Condensation releases H2O and forms a chemical bond, hydrolysis requires H2O to break a bond like amino acids joined by condensation reactions to form polypeptides.

Question 4

Universal solvent:

Answer 4

1. Water is a polar molecule. Positive end of a water molecule is attracted to a negative end, ions and polar molecules can be dissolved.
2. Water can dissolve other substances like oxygen, urea, inorganic ions, enzymes. Most metabolic reactions take place in solutions.
3. The advantage of metabolic reactions taking place in solution is that the random movement of molecules increases, so the rate of successful collisions increases.