课程名称︰普通化学甲下 课程性质︰必修 课程教师︰佘瑞琳 开课学院：理学院、生农学院 开课系所︰地质系、大气系、农化系 考试日期（年月日）︰2012/5/16 考试时限（分钟）：120分钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : Gas constant: R = 8.314 J/mol-K = 0.082 L-atm/mol-K I.Multiple choices questions (2 points per question, 30%) 1.For the following process, choose thatΔS is negative, assuming each occurs at constant temperature. + - (a)H2O(l)→H2O(g) (b)Ag(aq)+Cl(aq)→AgCl(s) (c)4Fe(s)+3O2(g)→2Fe2O3(s) (d)2NO2(g)→N2O4(g) 2.At 25℃, choose the one with the highest standard molar entropy. (a)I2(s) (b)Br2(l) (c)H2(g) (d)HBr(g) 3.For certain chemical reaction, ΔH°=-35.4kJ and ΔS°=-85.5J/K. (a)the reaction is exothermic. (b)the reaction lead to an increase in the randomness of the system. (c)the value of ΔG° for the reaction at 298K is negtive. (d)the reaction is nonspontaneous at 298K. 4.For the isothermal expansion of a gas into a vacuum, (a)w=0 (b)q=0 (c)ΔE(internal energy)=0 (d)This is a spontaneous process 5.For a spontaneous redox reaction which of the following must be true? (a)Ecell>0 (b)ΔSuniverse<0 (c)ΔG<0 (d)K(equilibrium constant) <0 6.Underground pipeline made of iron is connected to a piece of metal to protect from corrosion. (a)The metal should be more active than iron. (b)Magnesium could be used as the metal. (c)The process is called cathodic protection. (d)The iron pipeline is acting as sacrificial anode 2+ + 7.For a voltaic cell: Fe(s)│Fe(aq)║H(aq)│H2(g)│Pt(s) (a)Fe(s) is the anode. (b)Pt(s) is the positive electrode. (c)Electrons flow from Fe(s) to Pt(s). (d)At equilibrium the Ecell at 298K is 0.44 V. + 2+ 8.A voltaic cell utilizes the following reaction: Pb(s)+2H(aq)→H2(s)+Pb(aq), which of the following is true? (a)If the size of the lead electrode is increaced, the cell emf will be increased. (b)The pressure of the H2(g) is increased in the cathode compartment,the cell emf will be increased. 2+ (c)If Pb(NO3)2(s) is added to the anode compartment to increase the [Pb ], cell emf will be increased. (d)At 25℃, the standard free energy change of the reaction,ΔG°,is less than 0. 9.Predict which of these nuclei are especially stable. 131 235 222 12 (a) 35I (b) 92U (c) 86Rn (d) 6C 10.Which of the hollowing nuclie is likely to have the largest mass defect per nucleon: 4 23 56 238 (a)2He (b)11Na (c)26Fe (d) 92U 11.Which of the following can be done to shorten the half life of the radioactive of decay of Sr-90? (a)Heat it. (b)Add certain catalyst. (c)React it with carbonate to form an insoluble compound (d)None of these 16 1 13 12.What particle is emitted in the nuclear transmutation: 8O(1p,?) 7N? (a)an α particle (b)a β particle (c)a neutron (d)a proton 13.Of the following, which is the most damaging when ingested? (a)α emmiters (b)β emmiters (c)γ emmiters (d)positron emmiters 11 14. 6C is an unstable isotope. What type of radioactive decay would be expected? 0 4 0 1 (a)-1β (b)2He (c)+1β (d)0n 15.Radiation that causes ionization, called ionizing radiation. Which of the following electromagnetic radiation is ionizing radiation? (a)X-ray (b)β-ray (c)visible light (d)γ-decay II.Problems(70%) 1.The water gas reaction: CO(g)+H2O(g)→CO2(g)+H2(g) may be used for the production of hydrogen gas from low-grade fuels. (a)CalculateΔH°, ΔS°, and ΔG° for the reaction at 25℃. (b)Is this an endothermic or exothermic reaction? (c)Does the entropy of the system increase or decrease? (d)Is the reaction spontaneous at standard condition? (e)How is the rate of the reaction, fast or low? (10%) ──────────────────────────────── CO(g) CO2(g) H2O(g) H2O(l) H2(g) ──────────────────────────────── ΔH°f(kJ/mol) -110.5 -393.5 -241.8 -285.9 - ΔS°(J/mol-K) 197.6 213.6 188.7 69.96 130.6 ΔG°f(kJ/mol) -137.2 -394.4 -228.6 -236.81 - ──────────────────────────────── 2.For the Haber process at 25℃, N2(g)+3H2(g)←→2NH3(g), ΔH°=-92.38kJ and ΔS°=-198.3J/K. (a)CalculateΔG° and equilibrium constant, K, at 25℃. (b)Assume that ΔH° and ΔS° for the reaction do not change with temperature, give the value of ΔG° and equilibrium constant, K at 500℃. (c)Is the reaction favored by and increase in temperature? (10%) 3.(a)Write the chemical equation that defines the normal boiling point of liquid carbon tetrachloride, CCl4(l). (b)What is the value of ΔG° for the equilibrium in part(a)? (c)Use the data to calculate the normal boiling point of CCl4. (6%,p.811) ┌─────┬───────┬───────┐ │Substance │ΔH°f(kJ/mol) │ΔS°(J/mol-K) │ ├─────┼───────┼───────┤ │CCl4(l) │ -139.3 │ 214.4 │ ├─────┼───────┼───────┤ │CCl4(l) │ -106.7 │ 309.4 │ └─────┴───────┴───────┘ 4.The value of Ka for nitrous acid (HNO2) at 25℃ is 4.5*10^-4. (a)Write the chemical equation for the equilibrium that corresponds to Ka. (b)By using the value of Ka, calculate ΔG° for the dissociation of nitrous acid in aqueous solution. + - (c)What is the value of ΔG when [H ]=5.0*10^-2M, [NO2 ]=6.0*10^-4M, and [HNO2]=0.20M? (d)What is the value of ΔG at equilibrium? (8%, 19.85) 5.(a)Complete and balance the equation that occurs in basic solution: - 2- Cr(OH)3(s)+ClO(aq)→CrO4(aq)+Cl2(g) (b)Indicate the oxidant and reductant in the reaction. (4%, p.834) 6.Use the standard reduction potentials in Table 20.1 to calculate (a) the standard cell potential, E°; (b) the standard free-energy change,ΔG°; (c) the equilibrium constant, K, at 298K for the reaction. (6%, ex.20.10) + + 4Ag(s)+O2(g)+4H(aq)→4Ag(aq)+2H2O(l) TABLE 20.1‧Standard Reduction Potential in Water at 25℃ E°red(V) Reduction Half-Reaction ────────────────────────────── - - +2.87 F2(g)+2e →2F(aq) - + - 2+ +1.51 MnO4(aq)+8H(aq)+5e →Mn(aq)+4H2O(l) - - +1.36 Cl2(g)+2e →2Cl(aq) 2- + - 3+ +1.33 Cr2O7(aq)+14H(aq)+6e →3Cr(aq)+7H2O(l) + - +1.23 O2(g)+4H(aq)+4e →2H2O(l) - - +1.06 Br2(l)+2e →2Br(aq) - + - +0.96 NO3(aq)+4H(aq)+3e →NO(g)+2H2O(l) + - +0.80 Ag(aq)+e →Ag(s) 3+ - 2+ +0.77 Fe(aq)+e →Fe(aq) + - +0.68 O2(g)+2H(aq)+2e →H2O2(aq) - - - +0.59 MnO4(aq)+2H2O(l)+3e →MnO2(s)+4OH(aq) - - +0.54 I2(s)+2e →2I(aq) - - +0.40 O2(g)+2H2O(l)+4e →4OH(aq) 2+ - +0.34 Cu(aq)+2e →Cu(s) + - 0[defined] 2H(aq)+2e →H2(g) 2+ - -0.28 Ni(aq)+2e →Ni(s) 2+ - -0.44 Fe(aq)+2e →Fe(s) 2+ - -0.76 Zn(aq)+2e →Zn(s) - - -0.83 2H2O(l)+2e →H2(g)+2OH(aq) 3+ - -1.66 Al(aq)+3e →Al(s) + - -2.71 Na(aq)+e →Na(s) + - -3.05 Li(aq)+e →Li(s) ────────────────────────────── + 2+ 7.If the potential of a Zn-H cell iis 0.45V at 25℃ when [Zn ]=1.0M and + P(H2)=1.0atm, what is the H concentration? (4%, ex.20.12) 8.Write nuclear equations for the followings. (6%, ex.21.2) 201 (a)mercury-201( 80Hg) undergoing eletron capture; 231 (b)thorium-231( 90Th) decaying to protactinium-231. 131 (c)Ioding-131( 53I), used to treat hyperactive thyroid glands, decay by producing a β particle. 9.A rock contains 0.275 mg of lead-206 for every milligram of uranium-238. The half-life for the decay of uranium-238 to lead-206 is 4.5*10^9 yr. (a)Calculate the decay constant. (b)How old is the rock? (6%, ex.21.7) 10.Two of the radioactive isotopes found in the fallout from nuclear 131 90 explosions or accidents are I, with a half-life of 8.0 days, and Sr, with a half-life of 28. yr. (a)How long will it take to take to each isotope to decay to 50% of its initial concentration? (b)Which isotope has the most serious long-term effects? (c)Briefly state the effects of these radioisotopes on health. (10%) ※注:试卷上有附完整周期表 --

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