Homework Problems in Nuclear Chemistry
1. To the best of your
ability, describe the nucleus of an atom.
2. Compare β-
and electrons.
3. Calculate the binding
energy (in MeV and J/mol) and binding energy per nucleon for 136 Xe
(135.9072 daltons), 208Pb
(207.9766 daltons) and 28Si (27.97693 daltons). Which nucleus is the most stable?
4. Write the nuclear
reactions for the following
a)
the α decay of 238Pu b)
the negatron decay of 60Co
c) the
positron decay of 11C d)
the electron capture decay of 208Bi
e)
the neutron-induced fisson of 235U into 144Ba, ? and two
neutrons
f) 238U(12C,
4n)246Cf g)
238U(n,γ)239U
5. Radioactive 222Rn is known to
accumulate in basement of buildings and constitute a health risk.
a)
What is the parent primary natural radionuclide the produces the 222Rn?
b)
Write the reaction for the nuclear decay of radon-222.
c)
Why are none of the intermediate radionuclides (or the parent) considered a
health risk?
6. Predict a reasonable decay
mode for each of the following. Write
the decay reaction and explain your reasoning.
a) 243Am b) 17F c) 49Ca d) 181Ir
7. Plutonium-238 has been
used as a source to power heart pacemaker batteries. Its half-life is 87.74 year. Calculate the activity in units of curies for
0.25 g of pure plutonium-238 used is a pacemaker battery. Why is it a good power source in a pacemaker?
8. What is the activity, in
Ci, of a γ-ray source that emits a single 1.67 MeV γ-ray per
disintegration, if the dose received at a distance of 1.0 m from the source is
337 mrad/h?
9. A 60Co source
(t1/2 = 5.2714 y) that had an
initial activty of 5.0 Ci has been in a laboratory for 15 years. Calculate the exposure rate 3.0 ft from the
source. Assume there is no shielding
around the source and remember to account for decay of the source. The value of
n is 1 for both the the 60Co
γ-rays (which have energies of 1.3325 MeV and 1.1732 MeV) and the
β-ray has an energy of 0.318 MeV.
10. What quarks would make up π-? Hint: p + π- <==> n
11. For stable isotopes, the N/Z ratio
(neutrons/protons) is about one for light elements and increases as the
elements get heavier. Use the
semi-empirical binding energy equation to qualitatively explain this.
12. Why can you get energy from both fission and
fusion. Under what circumstances will
this statement be true?
13. Xenon-135 has a huge
neutron capture cross section. Explain.