140A1stW08 - Chemistry 140A Whitesell Winter Quarter 2008 First Midterm Exam Monday January 28 first name middle initial last name Student ID

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Unformatted text preview: Chemistry 140A Whitesell Winter Quarter, 2008 First Midterm Exam, Monday January 28 first name middle initial last name Student ID Number Quest 1 2 3 4 5 6 7 8 9 10 11 12 total Points 4 4 4 4 4 4 9 9 12 16 17 13 100 score Your answers to this exam are to be only your own work. You may use no written information during this test period other than the five pages of this exam. You may not use the back of any pages for answers. Up to one week after your exam is returned you may submit it for regrading if and only if you have made NO marks on the exam except for a star (*) next to the number(s) of the question(s) you would like regraded. your signature (read the above before signing) To request regrading, sign below and check the appropriate boxes. your signature I would like the questions marked with a star (*) regraded (check box at right) If you feel that we have made an addition error in your score, check the box at the right 1 23 4 5 6 7 8 90 1 23 4 5 6 7 8 90 1. The activation energy difference necessary to produce a rate difference of 1000:1 is: 4.1 kcal/mole 13.5 kcal/mole 1.35 kcal/mole 2.7 kcal/mole 2. The pKa of H2O is: 7 15.6 60 14 3. Hybridization of a 2s and a two p orbitals results in: 3 sp hybrid orbitals 3 sp2 hybrid orbitals 2 sp hybrid orbitals 3 sp3 hybrid orbitals 4. The electronegativity of N is: 2.5 3.5 5. 3.0 4.0 The pKa of H2O is: 7 15.6 60 14 6. In heptane, all of the carbon atoms have hybridization of: sp sp3 sp2 sp4 7. Draw electron-dot pictures for NH3 and –OH including all lone pairs of electrons. Place your answers in the boxes below. 8. Using line notation, draw structures for the following compounds in the boxes provided. 3-ethylheptane 3-isopropylpentane 3,3-diethylpenane Your signature (in ink)______________________________________________ 2 9. Label all carbon atoms in 2,3,3-trimethylpentane as primary, secondary, tertiary, or quaternary using the symbols: 1˚, 2˚, 3˚, 4˚. Use the structure provided in the box below 10. Draw the expected potential-energy diagram for the rotation about the C3-C4 bond in 2-methylpentane. Only relative energy positions are required, you need not and should not include any energy values. Include the Newman projections of each staggered conformation. Include a Newman projection of the highest energy eclipsed conformationPut your answer in the box below. 3 4 Your signature (in ink)______________________________________________ 3 11. In the structures shown below, draw circles around all methyl groups and rectangles around all ethyl groups. Do not guess. A wrong answer will remove credit for a correct one. Your signature (in ink)______________________________________________ 4 12. Draw all possible constitutional isomers of C7H16 (as line notations, no atoms, only bond lines). Put your answers in the boxes below. But one and only one isomer in each of the boxes below. If you duplicate an isomer, neither answer will receive credit. There may be more boxes than you need. A bonus will be award for perfect answers. Your signature (in ink)______________________________________________ 5 ...
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This note was uploaded on 10/16/2010 for the course CHEM 6B taught by Professor Crowell during the Spring '08 term at UCSD.

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