Chemistry 2710 Spring 2000 Test 1

Name:

Aids allowed: calculator, one 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.

Advice: Don't waste time. There should be plenty of time to answer all questions, provided you start by picking up the easy marks. Don't force yourself to work on the questions in the order in which they appear on this paper.

1. For the reaction of ozone with nitrogen monoxide ( ) at 340K, the following initial rate data have been obtained:

   

   1. Determine the empirical rate law and the value of the rate constant. [9 marks]

   2. Could this reaction possibly be elementary? Explain briefly. [2 marks]

2. Consider the mechanism

   

   1. What is the overall reaction? [4 marks]

   2. If , , and , what is the equilibrium constant for the overall reaction? [9 marks]

3. For the essentially irreversible reaction , the following data were obtained:

   

   1. Previous experiments showed that the rate did not depend on b. The order of the reaction with respect to A is either or 1. Can these data be used to determine the order? If so, report the order and rate constant. If not, demonstrate that the data are inadequate to this purpose. [9 marks]

      Hint: The amount of B which accumulates after a long time can be used to calculate the initial amount of A.

   2. Could this reaction possibly be elementary? Explain briefly. [2 marks]

4. Cell division is triggered (in part) by the accumulation of a protein called cyclin in a cell. Although the mechanism by which cyclin interacts with the cell-cycle machinery is complex, we can study a simplified version of this system by only considering cyclin accumulation and degradation.
   1. Suppose that the mechanism is

      

      (zero-order production, first-order degradation) where C represents cyclin. Write the rate law for the concentration of cyclin from this mechanism. [2 marks]

   2. Verify that

      

      is a solution to your rate equation if c(0)=0. [8 marks]

   3. Suppose that the rate constants appearing in the above mechanism have the values and . Moreover, suppose that cyclin must accumulate to a level of 15nmol/L to trigger division. How long does this take? [5 marks]