課程名稱︰無機化學一 課程性質︰必修 課程教師︰鄭淑芬 開課學院：理學院 開課系所︰化學系 考試日期（年月日）︰2013/01/09 考試時限（分鐘）：160 是否需發放獎勵金：是 （如未明確表示，則不予發放） 試題 : o o o ΔH = ΔH (Heat of formation)/ Ea = E Eb = E (Standard potential in A->acid) f A B B->base) 1. Many MX-type compounds with C.N. 6 have the NaCl structure, whereas few have NiAs structure. (a) Explain the difference of these two crystal structures and why NiAs structure is rare. (6%) (b) What characteristics of the compound are necessary to have the NiAs structure? (2%) 2. Flausthalite is a mineral composed of PbSe. The mineral adopts a Rock-salt type structure. The density of PbSe at 25 ℃ is 8.27 g/cm3. (Atomic weight: Pb=207, Se=79) (a) Calculate the length of an edge of the PbSe unit cell. (5%) (b) Calculate the distance between Pb2+ and Se2- ions in the structure. (3%) 3. Show the Born-Haber cycles and complete the following table (all values are in kilojoules per mole). (15%) ------------------------------------------------------------------------------ Compound ΔH 1st I.E. 2nd I.E. ΔH 1st E.A. 2nd E.A. ΔH,lattice ΔH (MmXn) (M,g) (M) (M) (X,g) (X) (X) (MmXn) (MnXn,s) NaCl 108 494 2185 122 349 -85 787 a Na2O 108 494 2185 249 141 26 b -409 CaCl2 368 654 1352 122 349 -85 2244 c ------------------------------------------------------------------------------ 4. Give explanations for the following phenomena and terms: (24%) (a) Metals that are very malleable and ductile have the ccp structure instead of hcp. (b) The melting point of SnCl2 is 246℃, while that of SnCl4 is -33℃. (c) Zeolites can be used as molecular sieves, and those contain sodium ions can be used to soften water. (d) All Hg(I) salts such as mercury(I) chloride are diamagnetic. (e) Cooper pairs are used to explain superconductivity. (f) Oxygen forms O8 structure under extremely high pressures. (g) The C-C distance in carbides of formula MC2 are in the range of 119-124pm if M = Ca and Sr, but in 128-130 pm if M = Y oe La. (h) The luminescence of GaAs can be tuned by doping different amount of P. 5. Given Ea = 0.771 V for Fe3+ + e- → Fe2+ and Ksp = 4.87*10^-17 and 2.79*10^-39 for Fe(OH)2 and Fe(OH)3, respectively, what is Eb for the Fe(OH)3 → Fe(OH)2 couple? (10%) 6. Knowing the Latimer diagram of Ea for Cl as follows: 1.20 1.18 1.19 1.70 1.63 1.36 Ea ClO4- －→ ClO3- －→ ClO2 －→ HClO2 －→ HClO- －→ Cl2 －→ Cl- (a) Construct the Latimer diagram of Eb for Cl. (15%) (b) What species are expected in the acid and base solutions of Cl2, and why? (6%) 7. Using the following Latimer diagram, which shows the standard potentials for sulfir species in acid solution (pH=0), construct a Frost diagram and indicate which of these sulfur species is the most stable one. (10%) +1.96 +0.16 +0.40 +0.60 +0.14 [S2O8]2- －－→　[HSO4]- －－→ H2SO3 －－→ [S2O3]2- －－→ S －－→ H2S 8. In the gas phase, BeCl2 forms a dimer of the following planar structure: Cl　　　　　 　y↑ ／ ＼　　　　　　｜ Cl－Be Be－Cl　　　 ｜ ＼ ／ ｜ Cl └－－－－→ x (a) Considering the valence orbitals of Be atom are in sp2 hybridization and a p-orbital perpendicular to the plane, use molecular orbital energy diagram to describe the bonding of the chlorine bridges "in the plane" of this dimer. (Considering only the 3px and 3py orbitals of Cl) (10%) (b) Considering each atom in the dimer contribute one p-orbital perpendicular to the plane for π-orbitals formation, show the energy level diagram and the electron distributions of these π-orbitals. (10%) ------------------------------------------------------------------------------ Given information: Conversion factor: 1eV = 1.6022*10^-19 J Plank's constant, h = 6.626*10^-34 J.s = 6.626*10^-27 erg.s Bolzmann's constant, k = 1.38066*10^-23 J/K Speed of light, c = 2.9979*10^8 m/s Mass of electron, me = 9.109*10^-31 kg Elementary charge, e = 1.602*10^-19 C Faraday's constant, F = 9.648*10^4 C/mol Gas constant, R = 8.314 J/K.mol = 0.08206 L.atm/K.mol Vacuum permittivity, εo = 8.854*10^-12 C^2/J.m Character table: C2v, C3v, C4v, D2h --

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