General Chemistry II Jasperse Nuclear Chemistry. Extra Practice Problems Radioactivity and Balancing Nuclear Reactions: Balancing Nuclear Reactions and Understanding which Particles are Involved he Stability of Atomic Nuclei: he Belt of Stability, Recognizing Whether An Isotope is likely to be stable or not, and predicting what it will do if it isn t. Rates of Radioactive Decay. Nuclear Half Lives and Radioactive Decay Math p Miscellaneous p9 p5 Mass Deficit. Binding Energy: e=mc p p7 Answer Key p Key Equations Given for est: E cell=e reduction + E oxidation Ecell = E [.59/n]log Q G = 96.5nE cell ( G in kj) log K = ne /.59 Mol e = [A time (sec)/96,5] time (sec)= mol e 96,5/current (in A) t = (t / /.693) ln (A o /A t ) ln (A o /A t ) =.693 t /t / E = mc (m in kg, E in J, c = 3x 8 m/s) Radioactivity and Balancing Nuclear Reactions: Balancing Nuclear Reactions and Understanding which Particles are Involves. Which of the following statements is true for a C? a. it has 6 s and 6 s b. it has s and s c. it has s and 8 s d. it has 6 s and 8 s e. none of the above Protons = Atomic Number Neutrons = Isotope Mass - Atomic Number Electrons = Atomic number (s) adjusted for charge if ionic (anion charge, extra electrons. Cation charge, fewer e's). Which of the following statements is true for a 37 Cl anion? a. it has 7 s, 8 electrons, and s b. it has 7 s, 6 electrons, and 7 s c. it has 37 s, 37 electrons, and s d. it has s, 8 electrons, and s e. none of the above 3. Which of the following statements is true for a 5 Mg + cation? a. it has s, electrons, and s b. it has s, electrons, and s c. it has s, electrons, and 3 s d. it has s, electrons, and s e. none of the above
. Beta emission is associated with a. conversion of a to a. d. decrease in mass number by and atomic number by. b. conversion of a to a. e. emission of γ rays. c. increase in mass number. 5. Electron-capture is associated with a. conversion of a to a. d. decrease in mass number by and atomic number by. b. conversion of a to a. e. emission of γ rays. c. increase in mass number. 6. Alpha emission is associated with a. conversion of a to a. d. decrease in mass number by and atomic number by. b. conversion of a to a. e. emission of γ rays. c. increase in mass number. 7. Positron emission is associated with a. conversion of a to a. d. decrease in mass number. b. conversion of a to a. e. emission of γ rays. c. increase in mass number. 8. he first step in the disintegration of uranium is 38 U à 3 h. What particle is emitted in this reaction? 38 U à 3 h +? a. α particle d. electron b. e. γ ray c. 9. he isotope Cr 53 is produced by the beta decay of which of the following: + a. 53 Mn b. 5 Cr c. 5 Cr d. 53 V e. 5 V +. What other particle is formed in the fusion of two s to form deuterium (H-)? H + H à H +? a. d. positron b. e. γ ray c. electron. Which particle is absorbed when 58 Fe à 59 Fe?? + 58 Fe à 59 Fe a. α particle d. electron b. e. γ ray c.
. he isotope i 8 is produced by the beta decay of which of the following: 3 a. 53 Mn b. 5 Cr c. 5 Cr d. 53 V e. 5 V + 3. Plutonium-38 is an α emitter and a compact heat source. Coupled with a Pbe thermoelectric device, it was once used as a very reliable electrical energy source for cardiac pacemakers. What is the product of the radioactive decay of plutonium-38? 38 Pu à α particle +? a. thorium-3 d. californium-6 b. uranium-3 e. plutonium-3 c. curium-. Nitrogen-3 decays by positron emission to produce 3 N à positron +? a. carbon-3. d. carbon-. b. oxygen-7. e. boron-3. c. boron-. 5. In the initial sequence of thorium-3 decay, an alpha particle is emitted followed by a beta particle. What is the product of these two decay steps? 3 h à α particle + β particle +? a. radium-8 b. actinium-8 c. thorium-8 d. francium-8 e. he correct answer differs from these possibilities. + 6. 75 Pt spontaneously decays into 7 Os. What is another product of this decay? 75 Pt à 7 Os +? a. α particle d. γ ray b. β particle e. He atom c. +e particle
7. Which isotope is produced when 6 Po decays by emitting an alpha particle followed by beta particles? a. b. c. 6 Po à α particle + β particles +? Po d. Po e. Po 8 Po Po + 8. Cobalt-56 decays by emitting a positron. What is the product? 56 Co à positron +? a. cobalt-55 d. iron-56 b. cobalt-56 e. iron-55 c. nickel-56 9. Radon- ( Rn) decays to polonium-6. What particle is emitted? a. beta d. alpha b. positron e. c.. Cobalt-6 decays to nickel-6. What particle is emitted? a. d. positron b. e. alpha c. electron. Uranium-38 decays to lead-6 through a series of nuclear reactions. Only α particles and β particles are emitted. How many α particles are emitted? a. d. 8 b. e. c. 6 +. If a nitrogen- nuclide captures an alpha particle, a is produced along with a. s. d. fluorine-8. b. boron-. e. carbon-7. c. oxygen-7.
5 he Stability of Atomic Nuclei: he Belt of Stability, Recognizing Whether An Isotope is likely to be stable or not, and predicting what it will do if it isn t. 3. What repulsive forces must be overcome for any element other than hydrogen to exist? a. he repulsion between s and other s. b. he repulsion between s and other s. c. he repulsion between s and s. d. he repulsion between positrons and electrons. e. he repulsion between s and electrons.. All elements with Z > 83 are a. Stable and unreactive c. Likely to decay by β emission. b. Radioactive. d. Likely to have / rations of less than or equal to :. 5. Light elements with Z < generally have a / ratios about equal to a..5. d..3. b..8. e..5. c... 6. he heaviest stable elements will generally have a / ratio about equal to a..5. c... b..8. d..5. See Periodic able for Help See Periodic able for Help 7. Which one of the following statements is not correct? a. Carbon- is unstable because it has too few s. b. All nuclides with Z > 83 decay into nuclides with smaller Z values. See Periodic able for Help c. Generally, the number of s in a nuclide is equal to or less than the atomic number. d. As the atomic number increases, the ratio of s to s in a nuclide increases. 8. Which one of the following statements is not correct? a. Oxygen-5 is unstable because it has too few s. b. Nucleons are held together in a nuclide by the electromagnetic force. c. All nuclides with Z > 83 decay into more stable nuclides with smaller Z values. d. As the atomic number increases, the ratio of s to s in a nuclide increases. e. Generally the number of s in a nuclide equals the number of s, or nearly so, when the atomic number is small, i.e., Z < 8. 9. Which of the following statements is false? a. U 38 is unstable, as expected based on the rule of 83 b. N 6 is unstable and radioactive because its / ratio is too high c. Nuclear reactions often produce large amounts of energy because small amounts of mass are converted into energy (see Einstein s famous equation, e=mc ) d. All radioactive isotopes decay completely and disappear within a short time ( year or less) 3. Predict the decay pathway for 9 Sr. (Strontium-88 is the most abundant stable isotope for Sr.) (Strontium-9 is a particularly hazardous radioactive isotope because, as an alkali earth metal, it will substitute for calcium in bones and teeth.) a. α emission d. γ emission b. β emission e. X-ray emission c. positron emission Normal his Nuclide n/p. Periodic table: find "actual" n/p ratio. Is the nuclide n/p ratio too high? *Convert n => p by beta emission 3. Is the nuclide n/p ratio too small? Convert p => n by either electron capture or positron emission. Does Z exceed 83? Reduce fast by alpha emission.
3. Np-37 is most likely to decay by a. emission. d. alpha emission. b. beta emission. e. electron capture. c. positron emission. Normal his Nuclide n/p 6. Periodic table: find "actual" n/p ratio. Is the nuclide n/p ratio too high? *Convert n => p by beta emission 3. Is the nuclide n/p ratio too small? Convert p => n by either electron capture or positron emission. Does Z exceed 83? Reduce fast by alpha emission. 3. What decay pathway is likely for cobalt-6? (Cobalt-59 is a stable isotope for Co.) (Cobalt-6, on the other hand, is used as a radioactive source approved by the FDA for irradiation of food. his process kills microbes and insects and can delay ripening.) a. α emission d. γ emission b. β emission e. X-ray emission c. positron emission Normal his Nuclide n/p 33. Nitrogen- is most likely to decay by a. emission. c. alpha emission. Normal his Nuclide n/p b. beta emission. d. or electron capture. Either positron emission 3. What type of emission is likely for Re-88? (Rhenium-85 is a stable isotope.) Rhenium-88 is a radioisotope for treatment of cancer. Normal his Nuclide n/p a. α d. γ ray b. β e. X-ray c. positron 35. Fact: 63 Zn is unstable and radioactive. Is its n/p ratio too high or too low? Which process could lead to stability? (Make sure that both parts of the answer are correct.) a. Its n/p ratio is too low. It could attain stability by either electron capture or positron emission. b. Its n/p ratio is too low. It could attain stability by beta emission. c. Its n/p ratio is too high. It could attain stability by electron capture. d. Its n/p ratio is too high. It could attain stability by beta emission. Normal his Nuclide n/p 36. Fact: 3 P is unstable and radioactive. Is its n/p ratio too high or too low? In that case, which process could lead to stability? (Make sure that both parts of the answer are correct.) a. Its n/p ratio is too low. It could attain stability by electron capture. b. Its n/p ratio is too low. It could attain stability by beta emission. c. Its n/p ratio is too high. It could attain stability by electron capture. d. Its n/p ratio is too high. It could attain stability by beta emission. e. Its n/p ratio is too high. It could attain stability by positron emission. 37. Which of the following nuclides are most likely to be unstable because they have too many s? I. carbon- II. sodium- III. silicon-6 IV. aluminum-7 V. phosphorous-3 a. only I d. III, IV, and V b. I and II e. all of these c. II and III Normal his Nuclide n/p. Periodic table: find "actual" n/p ratio. Is the nuclide n/p ratio too high? *Convert n => p by beta emission 3. Is the nuclide n/p ratio too small? Convert p => n by either electron capture or positron emission. Does Z exceed 83? Reduce fast by alpha emission.
7 Rates of Radioactive Decay. Nuclear Half Lives and Radioactive Decay Math 38. A half-life is a. constantly changing. b. half of the lifetime of an unstable nucleus. c. the time for one-half of an unstable nuclei to decay. d. independent of the rate constant for decay. t = (t / /.693) ln (A o /A t ) ln (A o /A t ) =.693 t /t / 39. he half-life of a radioactive isotope is. minute. In an experiment, the number of decay events was monitored in - minute intervals over a 5-minute period. Suppose 5 decay events were observed in the first minute. In the second minute, events were observed, and in the 5th minute, events were observed. a. 5, 5 d. 5, b. 5, 3 e. 5, 3 c. 5, 5 Min (Half/lives) Events Percentage 3 5. Uranium-38 decays to form thorium-3 with a half-life of.5 9 years. How many years will it take for 75% of the uranium-38 to decay? a. 9. years d. 9. 9 years b..5 9 years e. 3.8 9 years c..5 years ln (A o /A t ) =.693 (t /t / ) (Half/lives) Percentage 3. ritium, ( 3 H) is used in glowing EXI signs located where there is no electricity for light bulbs. If the half-life of tritium is.6 years, what percentage of the original quantity of the isotope is left in the sign after 8.5 years? (You should be able to both calculate exactly, but also be able to choose from among these options without a calculator.) a..63% d..5% b. 63.% e. 5.% c. 35.% ln (A o /A t ) =.693 (t /t / ). Iodine-3 has a half-life of 8. days and is used as a tracer for the thyroid gland. If a patient drinks a sodium iodide (NaI) solution containing iodine-3 on a uesday, how many days will it take for the concentration of iodine-3 to drop to 5.% of its initial concentration? a. 9 days d. 35 days b..8 day e..3 days c. 8. days (Half/lives) Percentage 3 5 t = (t / /.693) ln (A o /A t )
8 t = (t / /.693) ln (A o /A t ) ln (A o /A t ) =.693 t /t / 3. Phosphorus-3 is a radioactive isotope used as a tracer in the liver. How much phosphorus-3 was originally used if there is only 3.5 mg left in a sample after 88 h? (he half-life of phosphorus-3 is.3 days.) a..96 mg d. 7. mg b. 6.6 mg e. 7.9 mg c..7 mg ln (A o /A t ) =.693 (t /t / ). Carbon- measurements on the linen wrappings from the Book of Isaiah on the Dead Sea Scrolls indicated that the scrolls contained about 79.5% of the carbon- found in living tissue. Approximately how old are these scrolls? he half-life of carbon- is 573 years. a. 57 years d. 9 years b. 8 years e. 6 years c. 3 years t = (t / /.693) ln (A o /A t ) 5. he half-life of 8 F is 9.7 minutes. If radiolabeled Prozac were administered to a patient for a PE scan at 8: A.M. on Monday, at what time would its activity reach % of the original activity? a. 9:9 A.M., Monday d. : P.M., Monday b. 9:7 P.M., Friday e. 6:7 P.M., Monday t = (t / /.693) ln (A o /A t ) c. : A.M., uesday 6. he activity of a sample of gas obtained from a basement containing radon- was found to be 8 pci/l. his isotope has a half-life of 3.8 days. If no additional radon- entered the basement, how long would it take for the activity to decline to pci/l? a. about days d. a bit less than days b. a bit more than days e. about days c. about day t = (t / /.693) ln (A o /A t ) 7. A. g sample of wood from an archaeological site produced 37 β particles in a -hour measurement owing to the presence of carbon-, while a. g sample of new wood produced 96 β particles in the same period of time. he half-life of carbon- is 573 years. How old is the wood from the archaeological site? a. 573 years b. 865 years c. years d. 98 years e. he correct answer differs by more than years from the values given in A D. t = (t / /.693) ln (A o /A t )
9 Miscellaneous 8. Nuclear fission produces energy because a. s are produced. b. the total mass of the products is less than that of the reactants. c. the total mass of the products is more than that of the reactants. d. it is a very powerful chemical reaction. e. photons are produced. 9. Which of the following statements is true? a. Isotopes have the same number of s but have different numbers of s b. In order to overcome the repulsion between s, a strong nuclear force is required to hold a stable nucleus together c. In order to overcome the repulsion between s, a strong nuclear force is required to hold the nucleus together d. he higher the number of s in the nucleus the more stable it will be. e. none of the above 5. Nuclear fusion produces energy because a. s are produced. b. the total mass of the products is less than that of the reactants. c. the total mass of the products is more than that of the reactants. d. it is a very powerful chemical reaction. e. photons are produced. 5. Which type of radiation does the most tissue damage, but only when the emitter is internally ingested? a. α d. b. β e. β + c. γ 5. Which type of radiation has the greatest penetration ability? a. α d. b. β e. β + c. γ 53. Uranium-35 is the fuel in nuclear power plants. When a nucleus of uranium-35 captures a, the nucleus splits into two lighter nuclei and initiates a chain reaction. he chain reaction is driven by the emission of a. s. d. β particles. b. s. e. α particles. c. positrons. 5. he purpose of control rods in a fission reactor is to a. cool down the reactor fuel. b. prevent oxygen from reaching the fuel. c. absorb s generated in the fission process. d. absorb the electrons emitted in the fission process. e. enhance the capture process. 55. Electricity is produced from nuclear reactions by a. capturing the electrons that are emitted. b. accelerating electrons with rapidly moving s from the nuclear reaction. c. a process still not understood by scientists. d. using the energy to make steam to turn turbines. e. using the energy to accelerate electrons in wires.
Mass Deficit. Binding Energy: e=mc Key equation: E = mc (m in kg, E in J, c = 3x 8 m/s) 56. Nuclear fusion produces energy because a. s are produced. b. the total mass of the products is less than that of the reactants. c. the total mass of the products is more than that of the reactants. d. it is a very powerful chemical reaction. e. photons are produced. 57. What quantity of energy would be produced as one atom of plutonium-38 undergoes alpha decay? he nuclide mass of 38 Pu is 38.95 amu (3.953 g), and the nuclide mass of uranium-3 is 3.9 amu (3.886 g). Alpha particle mass is 6.665 g. he speed of light is.998 8 m/s. Initial: 3.953 x - - Final: (3.886 x - + 6.665 x - = 5.535 x -6 g = 5.535 x -9 kg a. 6. 7 J d..6 8 J b. 5. x J e.. J c. 7. J 58. What quantity of energy would be produced as. g of plutonium-38 undergoes alpha decay? he nuclide mass of 38 Pu is 38.95 amu (3.953 g), and the nuclide mass of uranium-3 is 3.9 amu (3.886 g). Alpha particle mass is 6.665 g. he speed of light is.998 8 m/s. a.. J d..3 x J b. 3.5 8 J e..7 9 J c. 6. 3 J 59. Calculate the nuclear binding energy per nucleon for the beryllium-8 isotope. Here are some helpful data: 8 Be isotopic mass 8.53 amu.393 3 g mass.7766 amu.67658 g mass.8669 amu.67976 g electron mass 5.85799 amu 9.93888 8 g speed of light.997958 8 m/s a..35 6 J/nucleon d. 8.766 J/nucleon b..879 9 J/nucleon e..879 5 J/nucleon c..37 J/nucleon
General Chemistry II Jasperse ANSWERS Nuclear Chemistry. Extra Practice Problems. D. A 3. C. A 5. B 6. D 7. B 8. A 9. D. D. B. C 3. B. A 5. B 6. A 7. B 8. D 9. D. C. D. C 3. B. B 5. C 6. D 7. C 8. B 9. D 3. B 3. D 3. B 33. D 3. B 35. A 36. D 37. B 38. C 39. B. D. C. D 3. B. D 5. D 6. B 7. D 8. B 9. B 5. B 5. A 5. C 53. B 5. C 55. D 56. B 57. B 58. D 59. C