Ch.20 - Nuclear Chemistry
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- What is the balanced nuclear equation for the alpha decay of plutonium-238? (a)
Problem 1
(b) (c) (d) - Fluorine-18 undergoes positron emission with a half-life of 1.10 x 10^2 minutes. If a patient is given a 250 mg dose for a PET scan, how long will it take for the amount of fluorine-18 to drop to 75 mg? (a) 56 minutes (b) 96 minutes (c) 132 minutes (d) 191 minutes
Problem 4
- A sample of 201Tl, a radioisotope used to determine the function of the heart, decays initially at a rate of 25,700 disintegrations/min, but the decay rate falls to 15,990 disintegrations/min after 50.0 hours. What is the half-life of 201Tl, in hours? (a) 73.0 hours (b) 105 hours (c) 1.56 x 10^-2 hours (d) 3.84 x 10^2 hours
Problem 5
- In a cave in Oregon, archaeologists found bones, plant remains, and fossilized feces. DNA remaining in the feces indi-cates their human origin but not their age. To date the remains, the decay rate was measured and found to be 2.71 disinte-grations/min per gram of carbon. Currently living organisms have a decay rate of 15.3 disintegrations/min per gram of carbon, and the half-life of 14C is 5715 years. How old are the remains? (a) 1460 years (b) 9900 years (c) 14300 years (d) 18600 years
Problem 6
- Calculate the binding energy a uranium-235 nucleus in units of MeV/nucleon. The mass of an 235U atom is 235.043 929, the mass of a proton is 1.007 28, the mass of a neutron is 1.008 67, and the mass of an electron is 5.486 x 10^-4. (1 MeV = 1.60 x 10^-13 J) (a) 2.84 MeV/nucleon (b) 1.70 x 10^3 MeV/nucleon (c) 11.3 MeV/nucleon (d) 7.62 MeV/nucleon
Problem 7
- Identify the true statement about nuclear power plants and nuclear weapons. (a) Nuclear power plants and nuclear weapons both use uranium enriched to about 90% U-235. (b) Nuclear power plants emit large amounts of CO2 just like coal burning power plants. (c) The United States produces less than 1% of its electrical power from nuclear energy. (d) A nuclear weapon explodes when two pieces of fission-able uranium-235 are pushed together to reach a critical mass.
Problem 8