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Homework Help: Thermal Physics - Absorbtion of oxygen in a magnetic field

  1. Mar 27, 2006 #1


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    Suppose that at most one [tex]O_2[/tex] can be bound to a heme group (see Problem 8), and that when [tex]\lambda(O_2) = 10^{-5}[/tex] we have 90 percent of hemes occupied by [tex]O_2[/tex]. Consider [tex]O_2[/tex] as having a spin of 1 and a magnetic moment of 1 [tex]\mu_B[/tex]. How strong a magnetic field is needed to change the adsorption by 1 percent at T = 300K? (The Gibbs sum in the limit of zero magnetic field will differ from that of Problem 8 because there the spin multiplicity of the bound state was neglected.)

    And for reference here is Problem 8 (however we were not required to do this question so I don't know the answer to this one either).:

    Problem 8 - Carbon Monoxide Poisoning:
    In carbon monoxide poisoning the CO replaces the [tex]O_2[/tex] adsorbed on hemoglobin (Hb) molecules in the blood. To show the effect, consider a model for which each adsorption site on a heme may be vacant or may be occupied either with energy [tex]\epsilon_A[/tex] by one molecule [tex]O_2[/tex] or with energy [tex]\epsilon_B[/tex] by one molecule CO. Let N fixed heme sites be in equilibrium with [tex]O_2[/tex] and CO in the gas phases at concentrations such that the activities are [tex]\lambda(O_2) = 1 x 10^{-5}[/tex] and [tex]\lambda(CO) = 1 x 10^{-7}[/tex], all at body temperature 37 derees Celcius. Neglect any spin multiplicity factors. a) First consider the system in the absence of CO. Evaluate [tex]\epsilon_A[/tex] such that 90 percent of the Hb sites are occupied by [tex]O_2[/tex]. Express the answer in eV per [tex]O_2[/tex]. b) Now admit the CO under the specified conditions. Find [tex]\epsilon_B[/tex] such that only 10 percent of the Hb sites are occupied by [tex]O_2[/tex].

    I know you guys ask for us to show that we've done some work on the question before submitting it but I really have no idea where to start on this one. I haven't talked to any classmates yet because they haven't started anything but if necessary I can see if I can get it started then post what I have before asking for help. I was just hoping someone here could get me going on some sort of solution.


    Note: Again, Problem 8 was not assigned so I'm assuming it is not required to be done so don't worry about that one.
    Last edited: Mar 27, 2006
  2. jcsd
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