Ch. 19 & 14ap  nuclear chemistry & kinetics   test  [65 points] Chemistry

Show your work in an organized manner, includes any relevant equation / formula, proper units in your work / answer, and the proper number of significant figures in your answer.

Academic Honesty:   The answers on this test are my own.  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 do not sign or violate any of the preceding items, your semester grade is a F.

                                                            Signature:  ___________________________

 

1.  Write the (hypothetical ?) nuclear reaction involving   [15 points]

a.  35 P undergoing positron emission:  __________________________

b.  the fission of 240 Np  -->  90 Sr  +  ________

c.  the alpha decay of 140 Ba:  ___________________________

 

2.  What is the age of an object that currently contains 2.5 g 14 C, which originally had 20.0 g 14 C.  The half-life of 14 C is 5.73 * 103 years.  [10 points]

 

3.  In the combustion of ethane

            C2 H6   +  O2   -->  CO2   +  H2 O

the rate of the consumption of oxygen is 10.0 mM / second.   [15 points]

a.  what is the rate of consumption of ethane ?

b.  what is the rate of appearance of carbon dioxide ?

c.  what is the rate of the reaction ?

 

4.  A chemical reaction has ∆H  =  45 kJ /mole, where the activation energy for the forward reaction (Ea,f ) is 35 kJ / mole.   [10 points]


a.  sketch the reaction energy profile, label Ea,b ; Ea,f ; ∆H; Ereactant ; Eproduct .

b.  What is the activation energy of the backward reaction  (Ea,b ) ? 


5.  What is the rate law (i.e. value of the exponents and rate constant, including its units) in the consumption of ethane (see # 3) based on the following (hypothetical ?) experimental data  [15 points]

Expt

[C2 H6 ]  (M)

[O2 ]  (M)

Rate (mM / s)

1

5.0

2.0

1.0

2

5.0

8.0

4.0

3

10.0

8.0

16.0