Nuclear chemistry & kinetics **test** [85 points] Chemistry

For problems involving calculations, show your work in an organized manner, includes any relevant formula / equation, the proper units in your work / answer, and the proper number of significant figures in your answer.

1. Fill-in the blank or write the (hypothetical) nuclear reaction. [15 points]

a. alpha decay of

^{230}Ra: __________________________b. beta-minus decay of

^{40}K: ________________________c.

^{35}S -->^{35}P + _______d.

^{18}O -->^{18}F + ______e.

^{235}Th -->^{ 55}Cr + _____

2. In the reaction: N 2 + 3 H 2 --> 2 NH 3 if , then [10 points]

a. = ____

b. = _____

3. The half-life of ^{131}I is 8.06 days. [15 points]

a. determine the decay constant

b. How long would it take for a 250 mCi sample of

^{131}I to decay to 100 mCi ?

4. An unknown radioactive isotope takes 15 years to decay from 735 Bq to 300. Bq. [15 points]

a. determine the decay constant

b. A sample of this isotope that originally contained 385 mCi, currently has 38 mCi. What is the “age” of the sample ?

5. For the reaction: N_{2} + 3 H_{2 } --> 2 NH_{3} , the following (hypothetical) experimental data was obtained:

expt |
Rate (mM/s) |
[N |
[H |

1 |
9 |
2 |
3 |

2 |
9 |
4 |
3 |

3 |
36 |
2 |
6 |

Determine the rate law (include the value of the exponents, the rate constant and the units of the rate constant) [15 points]

6. sketch and label (the axis of the graph & E_{a,f} , E_{a,b}, and ∆H) a reaction energy profile, where [15 points]

a. E

_{a,f}= 255 kJ /mole and ∆H = - 25 kJ /mole.b. E

_{a,f}= 325 kJ / mole and E_{a,b}= 275 kJ / molec. the effect of a catalyst on a reaction’s energy profile