Name: ________________________
Hour: ____ Date: ___________
AP Chemistry: 21HW
Directions: Complete the following problems.
Write a balanced equation for each.
1A.
Nickel-59, which is often analyzed in the
dating of meteorites, undergoes electron
capture.
1B.
Cesium-137, which is used to treat certain
types of cancer, emits a fast-moving electron.
Technetium-99, a radioactive tracer used
in nuclear medicine, undergoes -decay.
Americium-241, often used in smoke
detectors, emits a helium nucleus.
Polonium-210 undergoes -decay.
Aluminum-26 undergoes electron capture.
Fluorine-18 emits a positron.
Potassium-40 undergoes positron decay.
2A. Uranium-238 undergoes a series of  and  decays, finally ending up as lead-206. In the series, how many
 particles and how many  particles are produced?
2B. The complete decay of plutonium-239 is as follows: . What is the final stable
nucleus that results?
3A. Bohrium-265 was first produced by the bombardment of americium-243 with a beam of magnesium-26
nuclei. Some number of neutrons was also produced. Write the balanced reaction equation.
3B. In one fission reaction of uranium-235, a U-235 nuclide is struck with a slow-moving neutron, producing
cerium-144 and strontium-90. How many neutrons and -particles are also produced?
Several radioisotopes of vanadium and their half-lives are… V-47: 32.6 min; V-48: 16.0 days; V-54: 49.9 s
4A. Which of these isotope is the most stable?
Which is the “hottest”?
4B. How long would it take for 61.2 g of vanadium-48 to decay down to 28.7 g?
4C. How long would it take for 68.5% of a sample of vanadium-47 to decay?
5A. Technetium-99 decays by gamma emission and has a half-life of 6.01 hours. It is used in medical
diagnostics and is usually administered to patients in the form of the pertechnetate ion (TcO 4–). If a
patient is given 85.5 mg of potassium pertechnetate, what mass of Tc-99 remains after 3.00 days?
5B. Nuclear power was first used in warfare when the U.S. dropped an atomic bomb on Hiroshima, Japan on
August 6, 1945. What fraction of the strontium-90 (t1/2 = 28.8 years) produced by that explosion still
remained on August 6, 2012?
ANSWERS:
4B. 17.5 d
4C. 54.3 min
5A. 0.0104 mg
5B. 20.%
5C. Carbon-11 is a positron-emitter and has a half-life of 20. minutes. C-11 is given to medical patients who are
undergoing PET (positron emission tomography) scan diagnostics. If a patient is given a sample of
C-11, how long will it take for the amount of C-11 to decrease to 5.0% of the original amount?
6A. The Sun radiates about 3.7 x 1023 J of energy into space every second. By how many tons each second is
the mass of the Sun decreasing? (1 kg = 2.205 lbs and 1 ton = 2000 lbs)
6B. The Earth receives solar energy at the rate of about 1.8 x 1014 kJ/s. What mass of solar material is
converted into energy over a 24-hour period to provide the daily amount of solar energy to the Earth?
6C. Using the information from Q6A and Q6B, how many billion tons of coal would have to be burned every day
to provide the same amount of energy as the Sun provides the Earth in one day? Assume that coal
yields 32 kJ of energy per gram when burned.
Determine the binding energy per nucleon for each of the following, given the following masses:
mp+ = 1.00728 amu, mn0 = 1.00866 amu, and me– = 0.0005486
7A.
Carbon-12, assuming the atomic mass to be 12.0000 amu. Express your answer in J/nucleon.
ANSWERS:
5C. 86 min
6A. 4500 tons/s
6B. 1.7 x 105 kg
6C. 540 billion tons
7A. 1.23 x 10–12 J/nucleon
7B.
Thorium-218, assuming the atomic mass to be 218.013284 amu.
Given that 1 electron-volt (eV) = 1.60 x 10–19 J, express your answer in MeV/nucleon.
8A. If the mass defect for iron-63 is 0.583594 amu/atom, determine the atomic mass of Fe-63, in amu.
8B. Assuming its binding energy per nucleon is 1.3576 x 10–12 J/n, find the atomic mass of silver-117, in amu.
ANSWERS:
7B. 7.71 MeV/nucleon
8A. 62.94037 amu
8B. 116.9117 amu
9. Consider the following reaction to produce methyl
methanoate:
When this reaction is carried out with methanol
containing oxygen-18, the water produced does
NOT contain oxygen-18. How can this observation
be explained?
10. Recall that a positron is identical to an electron, except that it has a positive charge rather than negative, i.e.,
the positron is the antimatter particle of the electron. (Each has a mass that is 1/1836th that of a proton.) If
a positron and an electron annihilate each other on colliding, they produce two identical gamma
photons. Determine the wavelength of the gamma rays.
11. Nuclear power was used for the second (and hopefully last) time in warfare when the U.S. dropped an
atomic bomb on Nagasaki, Japan on August 9, 1945, three days after the bombing of Hiroshima. The
bomb that destroyed Nagasaki was a 25 kiloton device; that is, its destructive power was equivalent to
25 kilotons of TNT, where a ton of TNT is the energy equivalent of 4.2 billion joules. Assuming that the
fission of one mole of plutonium-239 releases 2.0 x 1013 J, approximately what mass of Pu-239
underwent fission at Nagasaki?
ANSWERS:
10. 2.4 x 10–12 m
11. 1300 g