next
Up: Back to the Chemistry 2710 test index

Chemistry 2710 Spring 2000 Test 2

Name:

Aids allowed: calculator, one tex2html_wrap_inline94 sheet of notes

Please write your answers in ink. If you have a graphing calculator, you can use it rather than hand drawing graphs. If you do use your calculator's graphing capabilities, explain in detail what you did (what graphs you drew, how you interpreted them, etc.). If you need to draw graphs by hand, graph paper is included at the end of this exam. Make sure to label your graphs with the question number.

  1. In quiz 8, we calculated the Michaelis constant and tex2html_wrap_inline96 for the reaction

    displaymath98

    catalyzed by the enzyme carbonic anhydrase. The kinetic constants of the forward reaction were found to be tex2html_wrap_inline100 and tex2html_wrap_inline102 . Note that water has no detectable effect on the rate, being present in great excess. Accordingly, from a kinetic point of view, the reaction is just tex2html_wrap_inline104 .

    In an initial rate study of the reverse reaction catalyzed by a 2.32nmol/L solution of the enzyme, the following data were obtained:

    tabular23

    1. Calculate tex2html_wrap_inline120 and tex2html_wrap_inline122 . [10 marks]

    2. Calculate the equilibrium constant for the reaction. From thermodynamics, we can calculate that tex2html_wrap_inline124 at tex2html_wrap_inline126 and tex2html_wrap_inline128 7. Is your answer in reasonable agreement with this value? [3 marks]

    3. Calculate tex2html_wrap_inline130 and tex2html_wrap_inline132 . [4 marks]

  2. The decomposition of ozone to form oxygen occurs by the reaction

    eqnarray42

    where X can be any of a number of inert species present in the atmosphere (nitrogen, argon, etc.).

    1. Identify a particularly reactive species present in this reaction. Argue, based on the existence of the highly reactive species identified, that a particular approximation can be used in deriving the rate law. [3 marks]

    2. What is the overall reaction? [2 marks]

    3. Use an appropriate approximation to derive a rate law for this reaction. [10 marks]

      Note: I expect some degree of simplification in your answer.

    4. If you were studying this reaction in controled laboratory conditions, you could systematically vary the pressure. How does the order of the reaction with respect to tex2html_wrap_inline134 vary with pressure? Focus particularly on the high- and low-pressure limits. What other changes in the empirical rate law would you observe as a function of pressure? [6 marks]
  3. In a series of enzyme inhibition experiments, the following data were obtained:

    tabular64

    1. Are these data compatible with competitive inhibition? Explain briefly. [5 marks]

      Hint: It might be sensible to use a graphical method to address at least part of this issue.

    2. On the assumption that this is an instance of competitive inhibition, calculate tex2html_wrap_inline144 , tex2html_wrap_inline146 and tex2html_wrap_inline148 . [7 marks]


next
Up: Back to the Chemistry 2710 test index

Marc Roussel
Mon Mar 27 08:36:02 MST 2000