課程名稱︰ 普通化學丙 課程性質︰ 物治系 醫技系 公衛系 職治系 護理系 藥學系 大一必帶 課程教師︰ 劉銘璋 開課學院： 理學院 開課系所︰ 化學系 考試日期（年月日）︰ 2014年 1月 8日 考試時限（分鐘）： 120 分鐘 是否需發放獎勵金： 是 （如未明確表示，則不予發放） 試題 : Final Exam of General Chemistry 1/8/2014 1. At 900°C, Kp =1.04 for the reaction CaCO (s) → CaO(s) + CO (g) 3 ← 2 At a low temperature, dry ice (solid CO ), calcium oxide, and calcium 2 carbonate are introduced into a 50.0-L reaction chamber. The temperature is raised to 900°C, resulting in the dry ice converting to gaseous CO . 2 For the following mixtures, will the initial amount of calcium oxide increase, decrease, or remain the same as the system moves toward equilibrium at 900°C? Ca: 40.08amu (6%) a. 655 g CaCO , 95.0 g CaO, P = 0.211 atm 3 CO2 b. 780 g CaCO , 1.00 g CaO, P = 1.04 atm 3 CO2 c. 715 g CaCO , 813 g CaO, P = 2.55 atm 3 CO2 -5 2. At 35°C, K = 1.6 x 10 for the reaction 2NOCl(g) → 2NO(g) + Cl (g) ← 2 In an experiment, 2.0 moles of pure NOCl are placed in a 2.0-L flask. Calculate the concentrations of all species at equilibrium. (6%) 3. Hydrogen for use in ammonia produced by the reaction Ni catalyst CH (g) + H O(g) ──────→ CO(g) + 3H (g) 4 2 ←────── 2 What will happened to a reaction mixture at equilibrium if a. H O(g) is removed? 2 b. the temperature is decreased (the reaction is endothermic)? c. an intert gas is added to a rigid reaction container? d. Ni catalyst is removed? e. the volume of the container is tripled? (5%) 4. Define enthalpy, entropy, and free energy. What information can be determined from these thermodynamic functions for a reaction? (10%) 5. For each of the following pairs of substances, which substance has the smaller value of S°? Give your reason. (6%) a. C (s) or C (s) graphite daimond b. C H OH(l) or C H OH(g) 2 5 2 5 c. N O(g) or He(g) 2 6. Consider the reaction 2POCl (g) → 2PCl3(g) + O (g) (6%) 3 ← 2 a. Calculate ΔG°for this reaction. The ΔG° values for POCl (g) and f 3 PCl (g) are -502 KJ/mol and -270. KJ/mol, respectively. 3 b. The value of ΔS°for this reaction is 179 J/K‧mol. At what temperatures is this reaction spontaneous at standard conditions? Assume that ΔH°and ΔS°do not depend on temperature. 7. Consider the system A(g) → B(g) at 25°C. (6%) a. Assuming that G°= 8996 J/mol and G°= 11,718 J/mol, calculate the A B value of the equilibrium constant for this reaction. b. Calculate the equilibrium pressures that result if 1.00 mole of A(g) at 1.00 atm and 1.00 mole of B(g) at 1.00 atm are mixed at 25°C. c. Show by calculations that ΔG = 0 at equilibrium. 8. In each of the following radioactive decay processes, supply the missing particle. (6%) 8 8 a. Li → Be + ? 3 4 239 235 b. Pu → U + ? 94 92 249 18 263 c. Cf + O → Sg + ? 98 8 106 9. For each pair of isotopes listed, predict which one is less stable and give your reason: (6%) 6 9 14 12 95 92 (a) Li or Li, (b) C or C, (c) Mo or Tc 3 3 6 6 42 43 10. (a) What kind of nuclear fission reactors are used in Taiwan? (b) Explain the functions of a moderator and a control rod in a nuclear reactor. (c) What is the SI unit of dose equivalent (energy dose of the radiation and its effectiveness in causing biologic damage)? (8%) 11. (a) What is a state function? Is work a state function? (b) State the first law of thermodynamics. (6%) 12. Calculate the internal energy change for each of the following. (6%) a. One hundred (100.) joules of work is required to compress a gas. At the same time, the gas releases 23 J of heat. b. A piston expands against 1.00 atm of pressure from 11.2 L to 29.1 L. In the process, 1037 J of heat is absorbed. (1L‧atm = 101.3 J) 13. Consider the following inital rate data for the decomposition of compound AB to give A and B: (6%) ┌───────┬───────────┐ │[AB] (mole/L)│Inital Rate (mol/L‧s)│ │ 0 │ │ ├───────┼───────────┤ │ │ -3 │ │0.200 │3.20 x 10 │ ├───────┼───────────┤ │ │ -2 │ │0.400 │1.28 x 10 │ ├───────┼───────────┤ │ │ -2 │ │0.600 │2.88 x 10 │ └───────┴───────────┘ a. Determine the rate law and the value of the rate constant. b. Determine the half-life for the decomposition reaction initally having 1.00 M AB present. 14. One mechanism for the destruction of ozone in the upper atmosphere is O (g) + NO(g) → NO (g) + O (g) Slow 3 2 2 NO (g) + O(g) → NO(g) + O (g) Fast 2 2 ────────────────────── Overall reaction O (g) + O(g) → 2O 3 2 a. Which species is a catalyst? Give your reason. b. Which species is an intermediate? Give your reason. c. Ea for the uncatalyzed reaction O (g) + O(g) → 2O (g) 3 2 is 14.0 kJ. Ea for the same reaction when catalyzed is 11.9 kJ. What is the ratio of the rate constant for the catalyzed reaction to that for the uncatalyzed reaction at 25°C? Assume that the frequency factor A is the same for each reaction. (6%) 15. Radioactive copper-64 decays with a half-life of 12.8 days. (6%) -1 a. What is the value of k in s ? 64 b. A sample contains 28.0 mg Cu. How many decay events will be produced 64 in the first second? Assume the atomic mass of Cu is 64.0. 64 c. A chemist obtains a fresh sample of Cu and measures its radioactivity. She then determines that to do an experiment, the radioactivity cannot fall below 25% of the initial measured value. How long does she have to do the experiment? 16. Consider the following graph of binding energy per nucleon as a function of mass number. (8%) a. What does this graph tell us about the relative half-lives of the nuclides? Explain your answer. b. Which nuclide shown is the most thermodynamically stable? Which is the least thermodynamically stable? c. What are fusion and fission reactions? d. What does this graph tell us about which nuclides undergo fusion and which undergo fission to become more stable? Support your answer. --

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