CHEM 1412. Chapter 21. Nuclear Chemistry (Homework) Ky Multiple Choice Identify the choice that best completes the statement or answers the question. ____ 1. Consider the following statements about the nucleus. Which of these statements is false? a. The nucleus is a sizable fraction of the total volume of the atom. b. Neutrons and protons together constitute the nucleus. c. Nearly all the mass of an atom resides in the nucleus. d. The nuclei of all elements have approximately the same density. e. Electrons occupy essentially empty space around the nucleus. ____ 2. A term that is used to describe (only) different nuclear forms of the same element is: a. isotopes b. nucleons c. shells d. nuclei e. nuclides ____ 3. Which statement concerning stable nuclides and/or the "magic numbers" (such as 2, 8, 20, 28, 50, 82 or 128) is false? a. Nuclides with their number of neutrons equal to a "magic number" are especially stable. b. The existence of "magic numbers" suggests an energy level (shell) model for the nucleus. c. Nuclides with the sum of the numbers of their protons and neutrons equal to a "magic number" are especially stable. d. Above atomic number 20, the most stable nuclides have more protons than neutrons. e. Nuclides with their number of protons equal to a "magic number" are especially stable. ____ 4. The difference between the sum of the masses of the electrons, protons and neutrons of an atom (calculated mass) and the actual measured mass of the atom is called the ____. a. isotopic mass b. mass deficiency c. nuclear mass d. decay mass e. critical mass These masses of subatomic particles may be useful for the following question(s). electron 0.00055 amu proton 1.0073 amu neutron 1.0087 amu ____ 5. Calculate the mass deficiency of . The actual mass of an atom is 16.9991 amu. a. 0.147 amu b. 0.153 amu c. 0.142 amu d. 0.148 amu e. 0.152 amu 1 HEM 1412. Chapter 21. Nuclear Chemistry (Homework) Ky These values may be useful for the following question(s). speed of light = 3.00 × 108 m/s 1 J = 1 kg•m2/s2 1 cal = 4.18 J ____ 6. What is the binding energy of an atom having a mass deficiency of 0.4721 amu per atom? Express your answer in kJ/mol of atoms. a. 2.77 × 1011 kJ/mol b. 4.25 × 1010 kJ/mol c. 4.25 × 1020 kJ/mol d. 5.26 kJ/mol e. 1.42 kJ/mol ____ 7. Calculate the nuclear binding energy in kJ/g of an isotope that has a mass deficiency of 0.6050 amu/atom. The isotope has a mass of 63.9280 amu. a. 3.48 × 1012 kJ/g b. 5.44 × 1010 kJ/g c. 1.89 × 1010 kJ/g d. 8.52 × 108 kJ/g e. 2.97 × 108 kJ/g ____ 8. Calculate the binding energy (in J/mol) for whose isotopic mass is 102.9055 amu. a. 8.75 × 1016 J/mol b. 2.86 × 1013 J/mol c. 8.57 × 1013 J/mol d. 2.86 × 105 J/mol e. 1.22 × 1014 J/mol ____ 9. Which isotope below has the smallest nuclear binding energy per gram? (No calculations are necessary.) a. b. c. d. e. ____ 10. A beta particle has a mass number of ____, a charge of ____, and a mass equal to that of a(n) ____. a. 4; 2+; helium nucleus b. 0; 1+; electron c. 0; 1−; electron d. 1; 0; neutron e. 1; 1+; proton ____ 11. The sum of the mass numbers of the reactants must equal which of the following? a. The number of nucleons which are transformed. b. The sum of the binding energies of the products. c. The sum of the atomic numbers of the products. d. The sum of the mass numbers of the products. 2 HEM 1412. Chapter 21. Nuclear Chemistry (Homework) Ky e. The sum of the atomic numbers of the reactants. ____ 12. Complete and balance the following equation. The missing term is ____. a. b. c. d. e. ____ 13. Complete and balance the following equation. The missing term is ____. a. b. c. d. e. ____ 14. A radioisotope of argon, , lies below the "band of stability." One would predict that it decays via ____. a. electron capture b. fission c. alpha emission d. neutron emission e. beta emission ____ 15. All nuclides with atomic number greater than ____ are beyond the band of stability. a. 43 b. 86 c. 83 d. 80 e. 90 ____ 16. Complete and balance the following equation. The missing term is ____. a. b. c. d. 3 HEM 1412. Chapter 21. Nuclear Chemistry (Homework) Ky e. ____ 17. A Geiger-Muller counter is a ____. a. spectrophotometer b. fluorescence detector c. gas ionization counter d. cloud chamber e. photographic detector ____ 18. The half-life of Tc-99 is 2.13 × 105 years. What is the value of the specific rate constant, k? a. 4.69 × 10−6 y−1 b. 0.693 y−1 c. 1.48 × 105 y−1 d. 3.25 × 10−6 y−1 e. 1.41 × 10−6 y−1 ____ 19. The half-life of polonium-211 is 0.52 s. What is the value of the specific rate constant, k? a. 1.50 s−1 b. 0.36 s−1 c. 0.75 s−1 d. 1.33 s−1 e. 0.67 s−1 ____ 20. Cobalt-60 has a half-life of 5.27 years. How long will it require for 10.5 mg of a 22.8-mg sample of to decay? a. 5.92 y b. 4.71 y c. 2.57 y d. 3.98 y e. 2.05 y ____ 21. The half-life of 33P is 25.3 days. How long will it take for 64.0 g to decay to 1.0 g? a. 150 d b. 210 d c. 350 d d. 100 d e. 120 d ____ 22. A 20.0-g sample of 277Th decays to 17.0 g in 3.00 days. What is the rate constant for the decay of this isotope? a. 0.054 d−1 b. 1.9 d−1 c. 0.12 d−1 d. 0.49 d−1 e. 1.50 d−1 ____ 23. If two-thirds of a radon-86 sample decays in 6.1 days, what is the half-life of this isotope? a. 1.18 d b. 3.8 d c. 0.41 d 4 HEM 1412. Chapter 21. Nuclear Chemistry (Homework) Ky d. 0.10 d e. 4.2 d ____ 24. A rock contains 3.008 mg of 238U and 0.624 mg of 206Pb. The half-life of 238U is 4.51 × 109 years. Estimate the age of the rock. a. 1.12 × 109 y b. 1.39 × 109 y c. 3.74 × 104 y d. 1.02 × 1010 y e. 6.12 × 108 y ____ 25. Which of the following would you expect to have the highest binding energy per nucleon? a. b. c. d. e. ____ 26. The major problem associated with the development of fusion for controlled energy generation is ____. a. containment of extremely high temperature plasmas b. containment of radioactive products of fusion c. relatively low energy yield per gram of fuel d. the resulting air pollution e. depletion of water reserves which serve as a source of fuel Dynamic Questions ____ 27. What is the percent activity of a radioactive sample (relative to its original activity) that has undergone three half-lives of decay? a. 3.13% b. 12.5% c. 25.0% d. 6.25% e. 75.0% ____ 28. A sample of a radioactive isotope is found to have lost 34.9% of its original activity after 3.63 days. What is the decay constant of this isotope? a. 0.0825 d−1 b. 1.56 d−1 c. 0.290 d−1 d. 0.118 d−1 e. 1.15 d−1 ____ 29. When undergoes beta emission, what is the product nuclide? a. b. 5 HEM 1412. Chapter 21. Nuclear Chemistry (Homework) Ky c. d. e. ____ 30. Which of the following characterizes a beta ray? a. Carries a positive charge b. Is more penetrating than a gamma ray c. Is a product of natural radioactive decay d. Is attracted to the negatively charged plate in an electric field e. Two of the above ____ 31. When uranium-238 undergoes alpha decay, the symbol of the daughter nuclide (product nuclide) is: a. b. c. d. e. ____ 32. What is the binding energy in kJ/mol nucleons for copper-65? = 1.00783 g/mol = 1.00867 g/mol = 64.92780 g/mol a. 8.373 x 108 kJ/mol nucleons b. 4.129 x 1010 kJ/mol nucleons c. 2.684 x 1012 kJ/mol nucleons d. 5.495 x 1010 kJ/mol nucleons e. 8.454 x 108 kJ/mol nucleons Other 1. Matter has successfully been converted into energy in nuclear reactions. What do you think would have to happen in order to successfully convert energy into matter? 2. Make arguments for and against nuclear power. Use facts, not emotions, in your discussion. 3. Describe the sequence of events in a new star, which starts out with hydrogen atoms involved in fusion. What happens when the hydrogen supply is exhausted? Where do elements other than hydrogen and helium come from? 4. How is it possible that such a small amount of matter can be converted into such a tremendous amount of energy in a fusion reaction? 5.