452 FInal 2008 - Chemistry 452 End- of-term Examination Key...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Chemistry 452 22 August 2008 End- of-term Examination Key Professor G. Drobny Useful Constants and Conversions Universal Gas Constant= 8.31 / 0.0821 / R J mole K L atm mole K =⋅ = Faraday’s Constant= 96,458 / Coulombs mole ℑ= gravitational constant=g=9.8m/s 2 Avagadro’s Number=N A =6.02x10 23 molecules/mole 1 atm=101,325 Nt/m 2 =760 torr 1 bar=10 5 Nt/m 2 =0.986923 atm=750.052 torr 1 Nt/m 2 =1Pa 1 torr=1 mmHg 1000L=1m 3 Part 1: (18 points total) Topics for discussion and definition. Answer 3 out of the 5 questions. 1.1) Sketch Hills plots for the binding of oxygen to myoglobin and to hemoglobin. Explain any differences in these plots in terms of models of binding between the oxygen ligand and the transport proteins. Myoglobin has a single oxygen binding site so its Hill plot is a straight line with slope =1. On the other hand, hemoglobin (Hb) has four oxygen binding sites. At low oxygen pressure the system is dominated by an equilibrium between free Hb and Hb with a single site occupied. This part of the plot has a slope of 1. at high oxygen pressure Hb with three sites bound is in equilibrium with fully bound Hb, and again the slope is 1. At intermediate pressures there occurs partly cooperative binding which produces a slope of 2.8.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
1.2) Explain how the surface pressure is measured with a Langmuir film balance. Sketch the experimental apparatus. What is the physical origin of the surface pressure? The Langmuir film balance is a trough with a float in the middle which separates pure water from water and surfactant. The surfactant layer is compressed by a moveable arm and the resulting force against the float is measured. The surface pressure is the measured force divided by the length of the float and yields the difference between the surface tension of pure water γ 0 and the surface tension of the solution γ 0 surface F P L γ ==− 1.3) Dipalmitoyl lecithin is a naturally-occuring detergent that is found at the air- water interface of the alveoli, which are the smallest air compartments in the lung. Explain the function of dipalmitoyl lecithin in the lung. Explain your answer in terms of surface tension and the effect of detergents on the surface tension of water. Solution: The alveoli are small air sacs in the lungs that are surrounded by tissue fluid. The pressure difference between the inside of an alveolus and the surrounding fluid is 2 inside outside PP P r ∆= = where γ is the surface tension and r is the radius of the alveolus. Because the alveoli are interconnected, an alveolus with small radius will have a higher internal pressure than a alveolus with a larger radius. The tendency will be for air to move from the small alveoli to larger alveoli, a process called coarsening. If coarsening occurs beathing will be difficult and the lungs will eventually collapse. To avoid this the pressure gradients between alveoli are diminished by lowering the surface tension with a lipid surfactant. The lower surface tension makes it easier to expand the lungs.
Background image of page 2
1.4) Fugacity. Define and describe two methods for measuring the fugacity coefficient.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/26/2010 for the course CHEM 452 taught by Professor Khalil during the Summer '08 term at University of Washington.

Page1 / 10

452 FInal 2008 - Chemistry 452 End- of-term Examination Key...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online