AP Chemistry 2015-­‐‑2016 Winter Break Extra Credit Name: Date: Per: In our normal course of study, we will cover chapters 1 – 11; 13 – 17; and 19 – 20. We will NOT formally cover the remaining chapters -­‐‑ #’s 12, 18, and 21 – 25. Chapters 21 and 18 are the most important of these “omitted chapters” since the material from them HAS been known to appear on the AP Exam in May. Since these chapters can be useful, I have decided to assign exercises from them as extra credit over the Winter break If you choose to do the extra credit from these chapters, the work will be due the first day we return from break at the beginning of the period. NO LATE PAPERS WILL BE ACCEPTED!! The exercises in each chapter will be worth about 10 points in the summative (test/quiz) category of your grade. You do not have to do all the exercises listed in the chapter to receive partial credit. The amount of credit you receive will be determined by the number and difficulty of the exercises you do complete. Happy Holidays!! -­‐‑Ms. Dandridge
Chapter 18: 1. Read pages /take notes: 702 – 733 NOTE – you can watch online tutorials for these chapters by searching on YouTube! 2. Do the following problems in your textbook for chapter 18: 18.1 18.21 18.3 18.25 18.10 18.27 18.12 18.29 18.13 18.36 18.14 18.37 18.17 18.38 18.20 Chapter 21 – Nuclear Chemistry: 1. Read and take notes on pages 830 – 860 NOTE – you can watch online tutorials for these chapters by searching on YouTube! 2. Do exercises: 21.1 21.12 21.3 21.13 21.4 21.29 21.5 21.30 21.8 21.31 21.9 21.33 21.11 21.34 3. The questions following, completed on separate sheets of paper. Include all of your work so that these can become valuable study tools prior to the AP exam. You MUST show all work and/or include a written explanation for multiple choice questions to receive credit. 1. Write equations for the following reactions: a. The production of 56Mn by neutron bombardment of 59Co. 15
b. The production of the new element dubnium by bombarding elements of 249
98 Cf with 7 N nuclei. 31
31
c. The bombardment of 27
particles to produce 15
P and the subsequent decay of 15
P 13 Al with to silicon by positron emission. d. The conversion of potassium-­‐‑40 to argon-­‐‑40 by electron capture. e. The production of carbon-­‐‑14 in the upper atmosphere by neutron bombardment of 147 N. 2. Why are radioactive isotopes of intermediate half-­‐‑lives more hazardous than radioisotopes with long half-­‐‑ lives or very short half-­‐‑lives? 3. Predict the radioactive ray of the following radioactive isotopes based upon their position relative to the band of stability: a. carbon-­‐‑14 b. krypton-­‐‑87 c. thorium-­‐‑230 d. phosophorus-­‐‑29 e. europium-­‐‑145 4. Calculate the quantity of energy released when one atom of uranium-­‐‑235 is split by the impact of a neutron into barium-­‐‑142 and krypton-­‐‑92 releasing one additional neutron. Then calculate the quantity of energy released when one gram of uranium-­‐‑235 undergoes fission in the same way. 235
1
142
92
1
92 U + 0 n → 56 Ba + 36 Kr + 2 0 n Atomic masses: 235
235.04 amu 92 U 142
56
92
36
Ba 141.92 amu Kr 91.92 amu 01 n 1.0087 amu 5. Charcoal retrieved from the site of Stonehenge in England has a carbon-­‐‑14 activity 62.0% that of carbon-­‐‑14 in living plants. Assuming that the abundance of carbon-­‐‑14 in the atmosphere has remained more or less constant for the past few thousand years, how old is the charcoal? The half-­‐‑life of carbon-­‐‑14 is 5730 years. 6. Strontium-­‐‑90 is a hazardous isotope present in the fallout from nuclear explosions. If 1.00 gram of strontium-­‐‑90 diminishes to 0.786 gram in 10 years, as measured by its activity, what is the half-­‐‑life of strontium-­‐‑90? 7. Technicium-­‐‑99 is prepared for medical imaging experiments by neutron bombardment of molybdenum-­‐‑98. The unstable molybdenum-­‐‑99 produced by this bombardment decays by β emission to an excited technicium-­‐‑99, which in turns relaxes to its ground state by emission. The technicium-­‐‑99 is itself radioactive and decays by β emission. Write the equations for this sequence of reactions. 8. If a radioactive isotope lies above the band of stability, which decay process would lead it toward the band, that is, form a more stable isotope? 9. Iron-­‐‑56 is the isotope with the highest binding energy per nucleon. Calculate the binding energy per nucleon from the following data: mass of proton = 1.007275 amu mass of neutron = 1.008666 amu mass of electron = 0.0005486 amu atomic mass of iron-­‐‑56 = 55.9349 amu Express your answer in units of J/nucleon. 10. 11. a. The fission of an americium-­‐‑244 isotopes produces iodine-­‐‑134 and molybdenum-­‐‑107. How many neutrons are also produced in each fission event? b. The fission of californium-­‐‑252 nucleus produces one barium-­‐‑142 nucleus and one molybdenum-­‐‑106 nucleus. How many neutrons are produced in this reaction? Moderator rods and control rods in a nuclear fission reactor serve different functions. What are their functions and how are they different? 21• Nuclear Chemistry P R A C T I C E T E S T 1. 2. 3. 4. 5. 6. 7. Henri Becquerel was best known for: (A) discovering x-­‐‑rays (B) coining the term "radioactivity" (C) discovering radioactivity (D) making new elements Marie Sklodowska Curie was best known for: (A) discovering Curium, Cm (B) learning about radioactivity (C) discovering x-­‐‑rays (D) sustained nuclear fission Iodine-­‐‑131 undergoes "beta decay". What other particle is produced? (A) Xe-­‐‑131 (C) I-­‐‑130 (B) Te-­‐‑131 (D) Sb-­‐‑127 What is the charge carried by a beta particle? (A) -­‐‑1 (B) 0 (C) +1 (D) +2 What type of radiation is simply a very energetic form of light? (A) alpha (C) gamma (B) beta (D) positron Md-­‐‑256 decays spontaneously with a half-­‐‑life of 1.5 hours. Which one of the following statements is true about Md-­‐‑256 after 3.0 hours? (A) All of the Md-­‐‑256 will be decayed. (B) 75% of the Md-­‐‑256 will remain. (C) 50% of the Md-­‐‑256 will remain. (D) 25% of the Md-­‐‑256 will remain. In a decay series of Th-­‐‑232, the first three steps involve an alpha decay and then two beta decays. What is the result of these decays? (A) Th-­‐‑228 (C) Fr-­‐‑224 (B) Rn-­‐‑228 (D) Pb-­‐‑207 Questions 8 -­‐‑ 10 refer to this graph: According to the above data, what is the half-­‐‑life of the substance? (A) 1.0 hrs (C) 3.0 hrs (B) 2.3 hrs (D) 8.0 hrs What percent of the original sample remains after 4 hours? (A) 80% (C) 60% (B) 75% (D) 40% Sketch a curve for a substance whose half-­‐‑life is 2.0 hrs. Match the scale to the graph shown above. Iodine-­‐‑131 has a half-­‐‑life of 8 days. What percent of a sample remains after 24 days? (A) 75% (C) 50% (B) 25% (D) 12.5% Which of the following describes what occurs in the fission process? (A) a heavy nucleus is fragmented into lighter ones. (B) a neutron is split into a proton and an electron. (C) two light nuclei are combined into a heavier one. (D) a particle and an anti-­‐‑particle turn completely into energy. The measured mass of neutral Li-­‐‑6 is 6.01512 amu. What is the mass defect of this isotope? mass electron 0.0005468 amu mass proton 1.007277 amu mass neutron 1.008665 amu (A) 0.03435 amu (C) 0.04947 amu (B) 0.01512 amu (D) 0.03038 amu 14. One mole of H2O has a mass of 18.0 grams or 0.0180 kg. Knowing that the speed of light, c, is 3.0 x 108 m/s, calculate the energy in one mole of H2O if all of its mass were changed to energy. [Note: 1 J = 1 kg·m2/s2] (A) 1.6 x 1015 J (C) 1.8 x 1018 J (B) 5.4 x 1010 J (D) 2.0 x 1013 J 15. The "control rods" in a nuclear reactor are designed to absorb ________ and are made of the element ____ (A) energy, Cd (B) uranium atoms, Pb (C) alpha particles, water (D) neutrons, Hf 16. The rate constant for decay of 218Po is 0.231 min-­‐‑1. What is the half-­‐‑life of this isotope? (A) 0.231 min (C) 13.6 min (B) 3.00 min (D) 4.33 min 8. 9. 10. 11. 12. 13. 17. Which of the following is a fission reaction? 18. Which of the following is a fusion reaction? In the nuclear equation, A
4
Z
2
the letters Z and A are, respectively (A) 90 and 242 (C) 94 and 234 (B) 94 and 242 (D) 90 and 234 Radioactive C-­‐‑14 has a half-­‐‑life of about 5,000 years. If a fossil is only about 6% as radioactive as expected for living tissue of the same mass, the age of the fossil is about: (A) 5,000 yrs (C) 20,000 yrs (B) 10,000 yrs (D) 40,000 yrs 210
21. The half-­‐‑life of Bi is 5.0 days. What is the rate constant for decay for this isotope, with the correct units? (A) 0.20 days (C) 0.14 days (B) 0.20 days-­‐‑1 (D) 0.14 days-­‐‑1 22. A 10.0 gram sample of thorium-­‐‑227 decays to 8.51 grams in a period of 3.00 days. What is the rate constant for this decay? (A) 0.0611 day-­‐‑1 (C) 0.0851 day-­‐‑1 (B) 0.0913 day-­‐‑1 (D) 0.0538 day-­‐‑1 23. A sample of neptunium-­‐‑234, with a half-­‐‑life of 4.40 days, is allowed to decay for 7.10 days. What percent of the original sample remains? (A) 19.9% (C) 30.6% (B) 61.9% (D) 32.7% 24. Cobalt-­‐‑64 decays by a first order process by the emission of a beta particle. The Co-­‐‑64 isotope has a half-­‐‑life of 7.8 minutes. How long will it take for 15/16 of the cobalt to undergo decay? (A) 7.8 min (C) 23.4 min (B) 15.6 min (D) 31.2 min 25. Referring to the figure below, which one of these corresponds to the fission process? (A) III → II (B) I →II (C) III→ V (D) V →IV 19. 238
92
20. U → X + He