Nuclear chem. & kinetics        test       62 points                                Chem

 

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

 

                                                                                                Signature:  ___________________

 

For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer. 

 

 

1.  fill-in the blank or write the nuclear reaction for the following hypothetical nuclear reactions.  [10 points]

 

a.  the alpha decay of 140Ba:  _____________________________

 

 

b.  the positron emission of 32Si:  ___________________________

 

 

c.  the beta decay of 27Al:  _________________________________

 

 

d.  230Ra  à   90Rb  +  _____ , which is an example of  ____________  (type of reaction)

 

 

e.  55Cr + 8Li  à  26Mg +  ___ , which is an example of ______________  (type of reaction)

 

2.  131I (half-life = 8.02 days) was detected in seawater near the damaged nuclear reactor in Japan.  How much time would it take for 99% of the radioactivity to disappear (assume that there is no new release of this isotope) ?  [10 points]


 

3.  In regards to the combustion of ethane:  C2H6 + O2 à  CO2  +  H2O,  fill-in the below table.  [12 points]

 

Rx rate

Δ C2 H6 /Δ t Δ O2 /Δ t Δ CO2 /Δ t Δ H2 O /Δ t

 

 

 

 

 

   5.0 mM / s

 

 

 

4.  Sketch / label the graphs that can be used to determine if a reaction:  A  à  B follows 0th, 1st, or 2nd order kinetics.  [15 points]

 

 

5.  Sketch / label the reaction energy profile for the reaction:  N2(g)  +  3 H2(g)  à 2 NH3(g).  The activation energy of the forward reaction is 100 kJ / mole.  Determine the activation energy of the backward reaction and the change in enthalpy of the reaction.  [15 points]