Chapter 19 – Nuclear Chemistry
26.
The only stable isotope of aluminum is aluminum-27. What type of radioactive decay should be expected from
Chapter 19 – Nuclear Chemistry
27. A balanced nuclear equation representing the beta emission of iodine-131 is which of the
following?
Chapter 19 – Nuclear Chemistry
28. A balanced nuclear equation representing the alpha emission of curium-242 is which of
the following?
Chapter 19 – Nuclear Chemistry
29. Which of the following nuclear processes results in an increase of atomic number in the
product element formed?
I. Alpha emission
II. Beta emission
III. Positron emission
IV. Electron capture
30. Which of the following nuclear processes does not change the mass number in the product
element formed?
I. Alpha emission
II. Beta emission
III. Positron emission
IV. Electron capture
Chapter 19 – Nuclear Chemistry
31. Which of the following nuclear processes results in an increase in the number of neutrons
in the product element?
I. Alpha emission
II. Beta emission
III. Positron emission
IV. Electron capture
32. A typical radius of an atomic nucleus is about
Chapter 19 – Nuclear Chemistry
33. The energy equivalent of a mass defect of – 0.1620 amu is which of the following?
34. The energy equivalent of a mass defect of – 0.1710 amu is which of the following?
35. 1 joule equals
Chapter 19 – Nuclear Chemistry
Chapter 19 – Nuclear Chemistry
37.
What is the nuclear binding energy per nucleon, in joules, for (atomic mass 24.985839 amu)?
[Data: (atomic mass) = 1.007825 amu; (mass) = 1.008665 amu; 1 kg = 6.022 1026 amu; c = 3.00 108 m/s]
38. Find the nuclear binding energy of potassium-40 (atomic mass = 39.9632591 amu) in
units of joules per nucleon. [Data: neutron mass = 1.674928 10–24 g; proton mass =
1.672623 10–24g; electron mass = 9.109387 10–28 g; NA = 6.0221367 1023 /mol; c =
2.99792458 108 m/s]
Chapter 19 – Nuclear Chemistry
39. Find the nuclear binding energy of uranium-234 (atomic mass = 234.040947 amu) in units
of joules per nucleon. [Data: neutron mass = 1.674928 10–24 g; proton mass = 1.672623
10–24 g; electron mass = 9.109387 10–28 g; NA = 6.0221367 1023 /mol; c = 2.99792458
108 m/s]
40.
Calculate the energy released in joules when one mole of polonium-214 decays according to the equation
[Atomic masses: Pb-210 = 209.98284 amu, Po-214 = 213.99519 amu, He-4 = 4.00260 amu.]
Chapter 19 – Nuclear Chemistry
41.
Determine how much energy is released when thorium-230 decays according to .
[Atomic masses: thorium-230 = 230.033127 amu; helium-4 = 4.002603 amu; radium-226 = 226.025403 amu]
42.
Determine how much energy is released when polonium-210 decays according to .
[Atomic masses: polonium-210 = 209.982857 amu; helium-4 = 4.002603 amu; lead-206 = 205.974449 amu]
Chapter 19 – Nuclear Chemistry
43. The only stable isotope of fluorine is . What type of radioactivity would you expect from the isotope ,
which has one fewer neutron?
Chapter 19 – Nuclear Chemistry
44. What fraction of radioactive atoms remains in a sample after six half-lives?
45. What fraction of radioactive atoms remains in a sample after five half-lives?
46. Carbon-11 is a radioactive isotope of carbon. Its half-life is 20.3 minutes. What fraction of
the initial number of carbon-11 atoms in a sample will remain after 81 minutes?
Chapter 19 – Nuclear Chemistry
47. Cobalt-60 is a beta emitter with a half-life of 5.3 years. Approximately what fraction of
cobalt-60 atoms will remain in a particular sample after 26.5 years?
48. Cobalt-60 is a beta emitter with a half-life of 5.3 years. Approximately what fraction of
the cobalt-60 atoms in a particular sample will remain after 32 years?
Chapter 19 – Nuclear Chemistry
49. If 12% of a certain radioisotope decays in 5.2 years, what is the half-life of this isotope?
50. If 24% of a certain radioisotope decays in 6.5 years, what is the half-life of this isotope?
51. Polonium-208 is an alpha emitter with a half-life of 2.90 years. How many milligrams of
polonium from an original sample of 2.00 mg will remain after 8.00 years?
Chapter 19 – Nuclear Chemistry
52. The half-life of 90Sr is 29 years. What fraction of the atoms in a sample of 90Sr would
remain 175 years later?
53.
The heaviest known isotope of hydrogen is called tritium, . It decays by beta emission, and has a half-life of 12.3 years.
What fraction of a tritium sample will remain after 5.20 years?
Chapter 19 – Nuclear Chemistry
54.
A rock contains 0.37 mg of Pb-206 and 0.95 mg of U-238. Approximately how many U-238 atoms were in the rock when it
was formed billions of years ago? (The half life for 238U → 206Pb is 4.5 109 yr.)
55.
A rock contains 0.37 mg of Pb-206 and 0.95 mg of U-238. The half-life of the decay series U-238 → Pb-206 is 4.5 109 yr.
Assuming no Pb-206 was present in the rock initially, how old is the rock?
Chapter 19 – Nuclear Chemistry
56. Charcoal found under a stone at Stonehenge, England, has a carbon-14 activity that is 0.60
that of new wood. How old is the charcoal? (The half-life of carbon-14 is 5,730 years.)
57.
Estimate the age of a bottled wine that has a tritium, 3H, content 60% that of freshly bottled wine. Tritium decays by beta
decay and has a half-life of 12.3 yr.
Chapter 19 – Nuclear Chemistry
58. How old is a bottle of wine if the tritium (3H) content is 25% that of a new wine? The
half-life of tritium is 12.5 years.
59. What would the atom ratio of 206Pb to 238U be in a uranium mineral from a rock that is 1.0
109 years old? t1/2(238U) = 4.5 109 yr.
Chapter 19 – Nuclear Chemistry
60. The radioisotope potassium-40 decays to argon-40 by positron emission with a half-life of
1.3 109 yr. A sample of moon rock was found to contain 78 argon-40 atoms for every 22
potassium-40 atoms. The age of the rock is
61.
The Rb-87/Sr-87 method of dating rocks is often used by geologists:
t1/2 = 6.0 1010 yr.
Estimate the age of a rock sample in which the present-day mole ratio of Rb-87 to Sr-87 is 36:1.
Chapter 19 – Nuclear Chemistry
62. What role does cadmium metal (Cd) play in a nuclear reactor?
63. Which one of the following statements about fission and fusion is false?