Sample Exam1_Key - 2 Chemistry 2521 Fall 2007; Midterm 1...

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Unformatted text preview: 2 Chemistry 2521 Fall 2007; Midterm 1 Exam This exam has 8 problems on 6 pages. Make sure your copy is complete and correct. Printed Name (Last, First) 4%; Scores: .°°>‘9‘S":'>S'°Nt“‘ \- Total: / 0 C7 1. (14 pts) In the provided boxes, finish drawing of the most important resonance form for each of the following species: (1 pt each missing Charge, bond, or a pair of non—bonding electrons) @ (EH (RI/p: ‘——* 3 2— .. 9 H3C—é:c:oz 3 2. (14 pts) Answer the following questions about types of bonds that are present in the molecule shown below (2 pts each answer; no partial credit; use 0 if there is no such bonds in the molecule): I Number of 0 bonds formed by overlap of sp2 and sp3 orbitals: Number of 0 bonds formed by overlap of sp3 and sp orbitals: 0 Number of 0 bonds formed by overlap of sp2 and sp orbitals: I Number of 0 bonds formed by overlap of s and sp3 orbitals: l Number of 0 bonds formed by overlap of s and sp orbitals: [ Total number of 0 bonds: 6 Total number of 717 bonds: 3 3. (15; 3 pts each) Give either the IUPAC name (including cis—trans designation, when appropriate) or the skeletal structure for each of the following compounds: (put answer in the box) (a) 1,4—dicyclopropylbutane (draw skeletal structure in the box) w ’ '13 '3 lei/3 r é C/é’fil"0/Q*]C’wcx{w CW, I CH 9 * of] (b) 3 0’73 3 l 2 z 4 f 6 (CH3)3CCH2C(CH3)2CH(CH3)2 2/ 2i 4, 4) 5”. pea, flag/,3 754%5 ayMC (write name in the box) (c) W f7¢4>15~ Pefl ’Z/«hmfl ’ 0674514474 (write name in the box) ((1) CH3 C2H5><:l’ (write name in the box) i W 2 _/ 0K (e) trans-1—isopropyl—2—methylcyclopropane (draw skeletal structure in the box) >”’V E 4. (6) Finish the drawing of the Newman projection of the most stable conformation of butane by placing appropriate substituents in the boxes on the bonds: (3 pts each substituent) 5. (12; 4 pts each) Complete the three-dimensional drawing of the most stable chair conformation for each of the following compounds. Use the provided, numbered cyclohexane ring; make sure to place the correct axial or equatorial substituents (including all hydrogen atoms) on the appropriately numbered carbon atom of the ring): (a) trans—1,4—dichlorocyclohexane (b) cis-1—isopropyl-Z-methylcyclohexane (c) trans-1—tert—butyl—3—methylcyclohexane 6. (10 pts) Answer questions (a)—(c) about the Bronsted acid-base reaction below by placing the identifying letters A-D below each structure on the answer lines. 0 O _ /H\ + H —CEN: ’ A + :CE N: A . B c D PKa = 9-3 pKa = 19.3 (a) (3 pts) Between structures A, I and D the weaker base is: D (b) (3 pts) The conjugate base of compound B is: j) (c) (4 pts) The species that predominate at equilibrium are (two letters): C l D 7. (4 pts) Use curved arrows to show the flow of electrons in the following reaction: (2 pts each arrow) “on H\ (19 \~ H + H-‘—-Cl: ———_. C H + =91: CH3/ 0/ .. CH/ \6/ 6 8. (25, 5 pts each) For each of the following questions (a)—(e) circle the item that is the correct answer. (a) Circle the conformation that has the largest diaxial interactions: CH3 H3C C(CH3)3 Mela CH3 C(CH3)3 CH3 (b) Which one of the following molecules has the Sp hybridized carbon atom? CH3COCH3 C24H50 CH3CH20H CH3OCH3 CHSCHO (CH3CN CH3NH2 (0) Which one of the following compounds is the strongest base? Lil HI H20 H3o+ LiZSO4 (CH3)3COH CH4 (d) Which of the following Newman projections represents 2,3-dimethylbutane? CH3 1 CH3 CH3 CH3 CH2CH3 H H 3C H H H H H H H H CH3 H CH3 H3C CH3 H H H H CH3 CH3 H CH(CH3)2 CH3 (e) Which of the following compounds is an aldehyde? 0 O & /U\/ /\/U\ CH3COZH 0 HO ...
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Sample Exam1_Key - 2 Chemistry 2521 Fall 2007; Midterm 1...

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