Friday, March 3, 2017

CHEM 418 Nuclear Chemistry, Winter 2017: Exam 3

Assigned: 1-Mar-17                                                               
1st Due Date: 8-Mar-17
2nd Due Date:  10-Mar-17                                                                         
Lecture 11:  Speciation
Lecture 12:  Uranium chemistry
Lecture 13:  Neptunium chemistry
Lecture 14:  Plutonium chemistry
Lecture 15:  Americium and Curium chemistry
Lecture 16:  Chemistry in reactor fuel
Lecture 17:  Separations
Lecture 18:  Application of Nuclear Material
Lecture 19:  Nuclear Forensics
Use lecture notes, textbooks, Chart of the Nuclides, Table of the Isotopes, and web pages.  Use the chart of the nuclides as your primary dataset for isotope half-life.   Show your work or references on a separate page and save electronically.  Submission of the work is not required for the 1st due date.  Please use 3 significant digits for your answers.  For scientific notation please use X.XXEX (i.e, 1230 as 1.23E3).
The first iteration of the exam is due 8-Mar-17.  The answers will be posted on 9-Mar-17.  Any incorrect answers can be resubmitted by 10-Mar-17. Changed answers will be worth 50 % of the original grade.  For the 2nd resubmission the work related to the changes must be shown.  Please post all questions to the blog.
There is an in-class meeting on the exam scheduled for Monday 6 March at 3:20 PM in Bagley 303A.

15 comments:

  1. Hi professor, I'm having a lot of trouble with question 1 which is the only problem I have yet to answer. I seem to be drawing a blank and I can't figure out how to determine the relative concentrations based on pH. Do you have any suggestions to get started? Thank you.

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    Replies
    1. There is an example on: https://en.wikipedia.org/wiki/Stability_constants_of_complexes

      look for the section on hydrolysis constants. This will provide some insight into the question. I will followup with more detail. I can also Canvas Conference on this if you wish.

      Delete
  2. You have K from the reaction. logK = -5.64

    H2O + PuO2 2+ <----> PuO2OH+ + H+

    For simplicity PuO2 2+ = M2+ and PuO2OH+ = MOH+

    K = [MOH+][H+]/[M2+], ignore water
    Kw = [OH-][H+] =1.01E-14

    One needs to solve for the reaction

    M2+ + OH- <----> MOH+

    B= [MOH+]/[M2+][OH-]

    So B and K have a common term, [MOH+]/[M2+]

    Substitute K into the equation for B

    K/[H+] = [MOH+]/[M2+]

    B = [MOH+]/[M2+][OH-] =K/[H+][OH-]
    with Kw = [H+][OH-]

    B = K/Kw

    One now has the value for B

    At a selected pH, [OH-] can be found from pH + pOH =pKw

    At any given pH one can calculate
    [MOH+]/[M2+] = B [OH-]

    From the question you have the sum of the relative concentrations is 1, so

    [MOH+] + [M2+] = 1

    One can use these two equations to solve for the terms [MOH+] and [M2+]

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  3. Thank you so much! viewed and submitted

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  4. Exam 3 has been submitted

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  5. Exam 3 submitted

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  6. Exam 3 has been submitted via email.

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  7. Exam 3 submitted on Canvas.

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  8. Exam 3 has been submitted via email.

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  9. Hi Ken,
    I did question 3.1 wrong but I am not sure how. I used the Lambert-Beer law with extinction (I/I0) = 0.65, extinction coefficient 410 and length = 1cm. Could you maybe give a tip to the correct solution?

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    Replies
    1. From the question A=0.35. So Beer's law

      A=ebc, A=0.35, e=410.

      Let me know if that helps, it should.

      Delete
    2. Thank you, I see what I did wrong now!

      Delete
  10. Exam 3 resubmission has been sent via email.

    ReplyDelete