1. Consider the following reaction in aqueous solution,
   5Br^-(aq) + BrO₃^-(aq) + 6H⁺(aq) --> 3Br₂(aq) + 3H₂O(l)

   If the rate of appearance of Br₂ at a particular moment during the reaction is 0.025 M s^-1, what is the rate of disappearance (in M s^-1) of Br^- at that moment?

    

2. Consider the following reaction at 25^oC,
   (CH₃)₃COH(l) + HCl(aq) --> (CH₃)₃CCl(l) + H₂O(l)

   The experimentally determined rate law for this reaction indicates that the reaction is first-order in (CH₃)₃COH and that the reaction is first-order overall. Which of the following would produce an increase in the rate of this reaction?

    

   1. increasing the concentration of (CH₃)₃COH
   2. increasing the concentration of HCl
   3. decreasing the concentration of HCl
   4. decreasing the concentration of (CH₃)₃CCl
   5. It is impossible to tell.

    

3. A certain first-order reaction has a rate constant, k, equal to 2.1 x 10^-5 s^-1 at 355 K. If the activation energy for this reaction is 135 kJ/mol, calculate the value of the rate constant (in s^-1) at 550 K.

    

4. Which of the following influences the rate of a chemical reaction performed in solution?
   1. temperature
   2. activation energy
   3. presence of a catalyst
   4. concentrations of reactants
   5. All of the above influence the rate.

    

5. Iodine-131, a radioactive isotope of iodine, is used medicinally as a radiotracer for the diagnosis and treatment of illnesses associated with the thyroid gland. The half-life of iodine-131 is 7.0 x 10⁵ seconds. If a patient is given 0.45 g of iodine-131, calculate how long it would take (in seconds) for 90.0% of the iodine-131 to decay. Recall: radioactive decay is a first-order process.
   
   
   
6. A student determined the value of the rate constant, k, for a chemical reaction at several different temperatures. Which of the following graphs of the student's data would give a straight line?
   1. k versus T
   2. k versus (1/T)
   3. ln k versus (1/T)
   4. ln k versus T
   5. ln k versus E_a
      
      
      
7. In the experiment, "How Can Spectrophotometric Methods Be Used to Determine the Order of a Chemical Reaction", it is necessary to remove invalid data points towards the end of the reaction. Which of the following statements best explains why this is necessary?
   1. The Spectronic 20 becomes unstable towards the end of the reaction.
   2. Towards the end of the reaction, the temperature of the solution is significantly different than the initial temperature of the solution.
   3. Towards the end of the reaction, the concentrations of the reactants are so high that it is difficult to measure them accurately.
   4. Towards the end of the reaction, the concentrations of the products are sufficiently high that the reverse reaction competes with the forward reaction.
   5. None of these.

   The next two questions are about this reaction:

   2N₂O₅ (g) <==> 4NO₂ (g) + O₂ (g)

    

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