Assignment 2 (Answer Scheme)
ERT 106
Sem 1 2010/1011
Topic: Water
Date of given
:
Date of submission:
1. Explain how the changes in temperature give effect to hydrogen bonds in water molecule.
Elaborate the situation with drawing of water molecules at every temperature level (25 marks).
Answer

Maximum number of hydrogen bonds which is four will formed when water has
frozen into ice. The bonds start to brake when there is enough energy for the
temperature to break those bonds. Hydrogen bonds are approximately 15% break
when ice is started to melt (10 marks).

Liquid water consists of ice-like clusters of molecules whose hydrogen bonds are
continuously breaking and forming hydrogen. As the temperature rises, the movement
and vibrations of the water molecules accelerate, and additional hydrogen bonds are
broken (10 marks).

When boiling point is reached, the water molecules break free from one another and
vaporize. There is high energy required to raise water’s temperature (5 marks).
Diagram of water in ice form- Hydrogen bond in water
2. Explain how the acids produced in metabolism are transported to the liver without greatly
affecting the pH of the blood (25 marks).
Answer

The acid produced during metabolism is lactic acid. The lactic acids are transported to the
liver for maintaining proper sugar, fatty acid, and amino acid concentration in the blood.
The system ensures that these substances pass through the liver before entering the
systemic circulation. The high concentration of lactic acid produced would not greatly
affect the pH of the blood because of the lactace buffer system (10 marks).

In metabolism, glucose will be converted to lactic acid
C6H12O6  2 CH3CHOHCOOH
Glucose
lactic acid
(5 marks)
Lactic acid then rapidly dissociates to form H+ and CH3CH(OH)COO− ions:
CH3CHOHCOOH  H+ + CH3CH(OH)COO−
Lactic acid

lactate
(5 marks)
When the pH is low, lactic acid will be converted to lactate so as the pH will increase. On other
hand, when the blood pH is low, lactate will converted to lactic acid (5 marks).
Assignment 2
ERT 106
Sem 1 2010/1011
Topic: Water
Date of given
:
Date of submission:
1. Explain how the changes in temperature give effect to hydrogen bonds in water molecule.
Elaborate the situation with drawing of water molecules at every temperature level (25 marks).
2. Explain how the acids produced in metabolism are transported to the liver without greatly
affecting the pH of the blood (25 marks).