Assignment 2 (Answer Scheme)

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 liverfor 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).