课程名称︰普通化学丙 课程性质︰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）︰99/06/24 考试时限（分钟）：120 是否需发放奖励金：是 试题 : General Chemistry, Final Exam June 24, 2010 1. What is the molarity of a methylamine solution, CH3NH2(aq), That has the same pH as 0.120 M NH3(aq)? (5%) (Kb of CH3NH2 = 4.2E-4, Kb of NH3 = 1.8E-5) 2. Knowing standard reduction potentials 2+ - o Pb + 2e → Pb E = -0.13 V; 2+ - o Ni + 2e → Ni E = -0.23 V; Determine the concentration of the ion in the following cells: (10%) 2+ 2+ (a) Pb(s)/Pb (aq, ?)//Pb (aq, 0.25M)/Pb(s) ε_cell = 0.050 V 2+ 2+ (b) Pb(s)/Pb (aq, ?)//Ni (aq, 0.15M)/Ni(s) ε_cell = 0.040 V 3. Knowing the following standard reduction potentials in an acidic solution (pH = 0) - 0.564 V 2- 2.27 V MnO4 ————→ MnO4 ————→ MnO2 (a) Write the balanced equations for these two reduction half reactions.(4%) - (b) What is the standard reduction potential of MnO4 —→ MnO2? (4%) 2- (c) Is MnO4 a stable species at pH = 0? Explain. (2%) 4. Write formulas for the following coordination compounds, and indicate the possible isomers if they have. (16%) (a) diamminedichloroplatinum(II) (b) tris(ethylenediamine)chromium(III) sulfate (c) pentaaquaiodoiron(III) nitrate (d) potassium dibromotetrafluoroferrate(II) (e) sodium tetracyanozincate(II) 5. Draw the orbital energy-level diagram showing the configuration of d-electrons on the metal ions in the following complexes. Also, indicate which of them are paramagnetic. (16%) 2- 2- (a) [NiCl4] (tetrahedral) (b) [Ni(CN)4] (square planar) 3- - (c) [CoF6] (octahedral) (d) [Ag(CN)2] (linear) 6. In solid corundum (Al2O3), Al(III) is surrounded by six oxide ions in an octahedral configuration. Substitution of Cr(III) results in ruby. The Cr2O3 solid has the same structure as corundum, but is green. The unit cell in corundum (Al2O3) has lattice constants a = 0.4763 nm and c = 1.3003 nm; the unit cell in Cr2O3 has lattice constants a = 0.4960 nm and c = 1.3599nm . Explain the different colors of Cr2O3 and ruby. (5%) 7. Name the following compounds. (12%) (a) CH3CH2CH3 (b) CH3CH=CHCH2CH3 (c) CH3CH=CHCH2CH=CHC2H5 (d) http://www.wretch.cc/album/show.php?i=yaujack&b=3&f=1008628908&p=5 (e) http://www.wretch.cc/album/show.php?i=yaujack&b=3&f=1008628909&p=6 (f) http://www.wretch.cc/album/show.php?i=yaujack&b=3&f=1008628910&p=7 8. Draw the structural formulas of the following compounds. (10%) (a) diethyl ether (b) 1-pentanal (c) 1,2-pentandiol (d) butanoic acid (e) methyl ethanoate 9, The pre-equilibrium and the stead-state approximations are two different approaches to deriving a rate law from a proposed mechanism. For the following mechanism, + k1 + CH3OH + H → CH3OH2 (fast in both directions) ← k(-1) + - k2 CH3OH2 + Br —→ CH3Br + H2O (slow) determining the rate law by (a) stead-state approximation, and (3%) (b) pre-equilibrium approximation. (3%) (c) Under what conditions do the two methods give the same answer? (2%) - (d) What will the rate law become at high concentration of Br ? (2%) 10. The enzyme catalase catalyzes the decomposition of peroxide. The uncatalyzed decomposition of peroxide has an activation energy of 82 kJ/mol , and the catalyzed reaction has an activation energy of 23 kJ/mol. (a) How much faster is the catalyzed reaction compared with the uncatalyzed reaction at 298 K? (4%) (b) How much faster is the catalyzed reaction at normal body temperature of 37 degrees C? (4%) 11. Writh (i) the structural formulas of the monomers of the following polymers , (ii) indicate them to be the addition polymers or condensation polymers, (iii) identify the intermolecular force between chains of polymers, and indicate (iv) which of them has the functional feature to form a rubber and (v) which of them can be a conducting polymer: (20%) (a) polyethylene (b) —(CH2C(CH3)=CHCH2)n— (c) http://www.wretch.cc/album/show.php?i=yaujack&b=3&f=1008628911&p=8 (d) http://www.wretch.cc/album/show.php?i=yaujack&b=3&f=1008628912&p=9 (e) http://www.wretch.cc/album/show.php?i=yaujack&b=3&f=1008628913&p=10 (f) http://www.wretch.cc/album/show.php?i=yaujack&b=3&f=1008628914&p=11 Useful informations: -1 -1 -1 -1 gas constant, R = 0.08206 atm L mol K = 8.314 J mol K Avogadro constant N_A = 6.022E23 /mol Planck's constant, h = 6.626E-34 J.s = 6.626E-27 erg.s 1 L.atm = 101.3 J 1 cal = 4.184 joule ~ The End, Have a Wonderful Summer Vacation! ~ --

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