Biophysical Chemistry I
due on 1995/10/20
HOMEWORK#2
1. For the following prossess calculate the indicated quantities for a system consisting of a mol of N2 gas. assume ideal gas behavior.
- (a) The gas initially at 10 atm pressure is expanded tenfold in volumn against a constant external pressure of 1 atm, all at 298 K. Calculate q, w, (delta)E and (delta)H.
- (b) After expansion of part (a). the volumn is fixed and heat is added until the temperature reaches 373 K. Calculate q, w, (delta)E and (delta)H.
- (c) What will be the pressure of the gas at the end of the process in part (b) ?
- (d) If the gas at 373 K is next allowed to expand against 1 atm pressure under adiabatic conditions (no heat transferred), will the final temperature be higher, remain unchanged, or be lower than 373 K? Explain your answer.
2. One mole of liquid water at 100 C is heated until the liquid is entirely converted to vapor at 100 C and 1 atm pressure. Calculate q, w, (delta)E and (delta)H for each of the following:
- (a) The vaporization is carried out in a cylinder where the external pressure on the piston is maintained at 1 atm throughout.
- (b) The cylinder is first expanded against a vacuum (Pex=0) to the same volumn as in part (a), and then sufficient heat is added to vaporize the liquid completely to 1 atm pressure.
3. If you set out to explore the surface of the moon, you would want to wear the space suit with thermal insulation. In such activity you might expect to generate roughly 4 KJ of heat per kilogram of mass per hour. If all this heat is retained by your body, by how much would your body temperature increase per hour owing to this rate of heat production? (Assume that your is roughly that of water.) What time limit would you recommand for a moon walk under this condition?
4. A reaction that is representive of those in the glycolytic pathway is the catabolism of glucose by complete oxidation to carbon dioxide and water:
C6H12O6(s) + 6O2(g) ---> 6CO2(g) + 6H2O(l)
Calculate (delta)H at 298 K for the glucose oxidation.
5. Use bond energy data to calculate the enthalpy of formation for each of the folloeing compounds at 25 C.
- (a) n-Octane, C8H18(g)
- (b) Naphthalene, C10H8(g)