Exam 2 2010 Crib - I Lgfj slate 8/, 0‘0. , Ci 1 30...

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Unformatted text preview: I Lgfj slate 8/, 0‘0. , Ci 1 30 Chemistry 241 Spring 2010 Exam 2 (1 1n grading 3. There are four questlons and a bonus. You should also have a Penodlc Table Potentlally UsefiJl Informatlon Radius Ratio Rules lg = 5.022 x1023 amu 1A=IO‘3cm lpm=10"2m l. (20 points) Cuprous bromide CuBr crystallizes in the zine-blend lattice and has a density of 4.98 g/cm3. (Atomic masses: Cu 63.55 g/mole; Br 79.90 g/mole) A. Sketch the conventional unit cell of this lattice. See Useful Information for an exploded view of the anion packing. U tetrahedral holes. B. Deduce the coordination number of Br' in the lattice. , C01“! 0 O {9L ’0er i " ‘ 7 t - w. 6’ 0"- ® Eu WW C. Estimate the shortest Cu+-Cu+ distance in the lattice. Show your work. (If you cannot Visualize the CuBr lattice, couch your answer in terms of the NaCl lattice for partial credit.) Ltd“ in all =7 9‘93? 2. (20 points) The Figure below depicts a partial MO scheme for the diatomic molecule FeO. For simplicity it includes only the 3d atomic orbitals of iron and the 2p atomic orbitals of oxygen. It incorporates all valence electrons of iron, but it omits the 25 electrons of oxygen. A. Name (6. g., “rt-bonding) any missing MO('s). Explain your reasoning, and indicate where it (they) tits (fit) in the diagram. Then Q in the electrons, and predict how many unpaired electrons the molecule should have. O__ + (ng I 71, +— T4. Z mots 3”»; ’ cfio aim WW % X2; e—bfl _ Effigy. B. Define a convenient axis system but the z-direction should be the internuclear gis. Then g \ sketch a contour of a@n-bonding the diagram, and shade the lobe(s) as appropriate. Indicate the constitutent "506st Does oxygen or iron play a bigger role in your drawing? Explain and illustrate with a drawing. x ’b not), b Jinnah Ls (Y l1 YT 3. (20 points) Assume for the sake of simplicity that a single MO diagram describes the valence orbitals of NO as well as its ionic forms and that the energy order is * ¥’ ¢&— fifliuh3flflwg> ‘é 10(20<17t<30‘<27r<40‘. A. Write the electronic configuration of NO. 1‘ He ‘- . 7.. a 4 2/ -l W Zg‘m' Ea“ if“ B. Predict the order of increasing bond strength for the following series, and explain your reasoning. Bo: N01"< “0 4ND,” C. Assume a similar MO scheme applies to CO. Identifl each of the following MO’s of the molecule and specify fll participating AO’s in each. J l ’ H "“-— " . i ii. iii. 4mm- SVmém [71, 4A. (20 points A and B total) Complete am balance the following reactions. i. co(g)+ H20(g) COL + Mia W ii. LiAlH4(s)+ SiH4 + MPWQUS gffif iii. Ca3P2(s) + énzog) » 3&(Qflqqf— 2 (Pg: 48. Account for the fact that HBr boils at a higher temperature than HCl but at a much lower temperature than HF. Compound T °C - H r . 419— ,F H/ P Emilia 34”" i2 H WW with M4 Jam 1%. I Mfutiottl: 1 Wm imtxkculs Mom-DAM may fix HQP Wcmtl mi Helge” m at /' MMEM flag: What a HP HUI as? Bonus (3 points) If M is the cation and X denotes the anion, what is the formula of the material that has a unit cell with X at each corner and M in the middle of each edge? X KXJSSI . l ...
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This note was uploaded on 03/20/2012 for the course CHM 24100 taught by Professor Professordavidr.mcmillin during the Spring '10 term at Purdue University-West Lafayette.

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Exam 2 2010 Crib - I Lgfj slate 8/, 0‘0. , Ci 1 30...

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