课程名称︰普通化学丙 课程性质︰系定必修 课程教师︰郑淑芬 开课学院：工学院 开课系所︰机械系 考试日期（年月日）︰2008/5/12 考试时限（分钟）：110分钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : (一) Multiple-Choice Questions (15%, -0.5 points per mistake) 1.Which of the following species is non-polar? (a)PF5 (b)NF3 (c)IF3 (d)SF4 (e)SiF4 2.Which of the following is a covalent compound? (a)Na2O (b)CaCl2 (c)Cl2O (d)CsCl (e)S8 3.Which one of the following molecules and ions will have a planar geometry? (a)PCl3 (b)BF4- (c)XeF4 (d)BrF5 (e)H3O+ 4.Decide on the appropriate hybridization of phosphorus in the ion PCl4- (Phosphorus is the central atom) (a)sp3 (b)sp2 (c)sp (d)sp3d (e)sp3d2 5.Which of the following statements relating to molecular orbital (MO) theory is correct? (a)Combination of two atomic orbitals produces one bonding and one antibonding MO. (b)A bonding MO is lower in energy than the two atomic orbitals from which it is formed. (c)Combination of two 2p orbitals may result in either σ or π-MOs. (d)A species with a bond order of zero will not be stable. (e)In a stable molecule having an even number of electrons, all electrons must be paired. 6.Which one, if any, of the follwing statements about the MO treatment of the bonding in benzene is correct? (a)MO theory uses resonance to describe the delocalized nature of the bonding in benzene. (b)Each pi-bonding orbital in benzene can hold up to 6 electrons. (c)MO theory predicts that benzene should be paramagnetic. (d)The lowest energy pi-bonding MO in benzene has two electrons forming hexagonal lobes, above and below the plane of the carbon atoms (e)Benzene has three pi-bonding orbitals. 7.Which of the following is true for pure oxygen gas, O2(g) at 25℃? (a)ΔHf°=0 (b)ΔHf°<0 (c)ΔGf°=0 (d)ΔGf°<0 (e)S°>0 8.Which of the following is true for a system at equilibrium? (a)ΔS°(sys)=ΔS°(surr) (b)ΔS°(sys)=-ΔS°(surr) (c)ΔH°(sys)>0 (d)ΔG°(sys)=0 (e)ΔG°(sys)<0 (二) Single Choice Questions (18%, 3 points per question) 9.Calculate ΔS°for the reaction: 2SO2(g) + O2(g) → 2SO3(g) S° in J/mol‧K for: SO2(g)=248.1 SO3=256.6 O2(g)=205.0 (a)-537 J/mol‧K (b)+145 J/mol‧K (c)-188 J/mol‧K (d)+547 J/mol‧K 10.What is the molar solubility of CaF2? (Ksp = 3.9 * 10^-11) (a)6.24*10^-6 M (b)4.41*10^-6 M (c)2.14*10^-4 M (d)9.27*10^-5 M 11.What is the pH of a 0.150M NaOH solution? (a)0.82 (b)3.05 (c)11.66 (d)13.18 12.Diethyl ether, used as a solvent for extraction of organic compounds from aqueous solutions, has a high vapor pressure which makes it a potential fire hazard in laboratories in which it is used. How much energy is released when 100.0g is cooled from 53.0℃ to 100.0℃? Boiling point: 34.5℃ Heat of vaporization: 351J/g Specific heat capacity, (CH3)2O(l): 3.74J/(g‧K) Specific heat capacity, (CH3)2O(g): 2.35J/(g‧K) (a)10.1kJ (b)13.1kJ (c)16.1kJ (d)45.2kJ (e)48.6kJ 13.The synthesis of the pesticide thionyl chloride (OSCl2) proceeds according to: SO3(g) + SCl2(l) ← → OSCl2(l) + SO2(g) If ΔG°=-106 kJ/mol for this reaction at 298K, what is the Keq at this temperature? (R = 8.314 J/mol‧K) (a)7.21*10^12 (b)3.50*10^14 (c)3.81*10^18 (d)1.19*10^20 14.From the values given for ΔH° and ΔS° at 298K, which of the following reactions is spontaneous under standard conditions at 298K? (a)2POCl3(g) → 2PCl3(g) + O2(g) ΔH°=572kJ ΔS°=179J/K (b)N2(g) + 3F2(g) → 2NF3(g) ΔH°=-249J ΔS°=-278J/K (c)N2(g) + 3Cl2(g) → 2NCl3(g) ΔH°=460kJ ΔS°=-275J/K (d)N2F4(g) → 2NF2(g) ΔH°=85kJ ΔS°=198J/K (三) Problems: 15.The equilibrium constant for NH4HS(s) ← → NH3(g) + H2S(g) at 25℃ is Kc = 1.6*10^-4 (a)What is the Kp value at this temperature? (4%) (b)When solid NH4HS and 0.450 mol of gaseous NH3 were placed into a 2.0L vessel at 25℃, what are the partial pressure of NH3 and H2S at equilibrium? (4%) (c)The van't Hoff equation shows the relationship between the equilibrium constant and the absolute temperature: ln(K1/K2) = -(ΔH(vap)/R)(1/T1-1/T2) Knowing that Kc is 2.96*10^-4 at 40℃, estimate the enthalpy of this reaction. (3%) 16.CdS can form a quantum dot solution. Determine the amount of Cd2+ and S2- left in solution if 450mL of 0.06M Cd(NO3)2 and 450mL of 0.08M Na2S are combined. Also, determine the pH of the solution. (Ksp of CdS = 3.6*10^-29 Ka1 of H2s = 9.1*10^-8, Ka2 of H2S = 1.1*10^-12) (10%) 17.What would happen if solid AgCl were added to a saturated solution of AgI? What are the concentrations of Ag+, Cl- and I- ions in the solution? (Ksp of AgCl = 1.8*10^-10, Ksp of AgI = 1.5*10^-16) (10%) 18.(a)Show the molecular orbital energy-level diagram of O2, indicating the bonding and anti-bonding orbitals. (5%) (b)Write the valence-shell electron configurations and bond orders of O2, O2- and O2(2-). (6%) (c)Put the above three species in the order of increasing bond length. (2%) (d)Which of the above three species are "paramagnetic"? (3%) 19.ZnS is a semiconductor with a band gap of 3.54eV. (a)Draw an energy-level diagram for this material, labeling the atomic orbitals, electron filling, valence band, conduction band and band gap. (b)If some of the sulfur is replaced with phosphorus, the conductivity of this material changes. Draw an energy-level diagram for the doped material indicating the filling of electrons. Is this material an n- or p-type semiconductor? (10%) 20.A reference book lists the following values for gallium at 298K. ──────────────────────────────────── Substance ΔHf°(kJ/mol) ΔGf°(kJ/mol) S°(J/mol K) ──────────────────────────────────── Ga(s)　　　　　　　0　　　　　　　　0　　　　　　　　 x Ga(l)　　　　　　　5.578　　　　　　0.0888　　　　　　59.25 Ga(g)　　　　　　　271.96　　　　　 233.76　　　　　　169.03 ──────────────────────────────────── (a)Estimate the noraml boiling point of gallium. (4%) (b)Gallium metal has a melting point of 29.8℃. Estimate the S° value of Ga(s). (6%) 21.Calculate the ΔE,ΔH,ΔS,ΔG, q and w values of isothermal expansion of the ideal gas at 298K by three different pathways. (18%) (三个Path,图略) Path 1 是两个装有活塞的烧杯(上端有开口)，活塞上放砝码当做下压力。 左罐放两个砝码，P1=6.0atm V1=0.40L 右罐一个砝码 P2=3.0atm V2没给 Path 2 是两个玻璃球，中间以附有开关的细管连接，有两组，第一组的左球里面是 充满气体，右球空，左球P1=6.0atm V1=0.40L，右球V=0.40L 第二组是开关打开，左右两球皆有气体，V2=V1+V Path 3 是两个附有活塞，可抽为真空的罐子(有盖)，活塞上放沙子当作下压力，将活 塞上端抽为真空，下端为气体。 左罐沙较多，P1=6.0atm V1=0.40L 右罐沙较少，P2=3.0atm V2没给 Useful informations: gas constant, R = 0.08206 atm‧L/mol‧K = 8.314 J/mol‧K Avogadro constant Na = 6.022*10^23 /mol Planck's constant, h = 6.626*10^-34 J‧s = 6.626*10^-27 erg‧s 1 atm = 760 mmHg = 760 Torr 1 eV = 96.487 kJ/mol Speed of light, c = 2.9979*10^8 m/s Mass of electron = 9.109*10^-31 kg --

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