Biology Midterm Exam

CHEMISTRY 140A NAME (please print) â y

MIDTEHM EXAM FrRsT ' ` LAST

OCT 29, 2012

Sofomons 10”’ ed (Cp 1 - 4)

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LAST NAME OF PERSON SEAIE'D T0 YOUR RIGHT: __

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- Please sign your name on the top of pages 1 through 4.
- Please check that you have 5 pages (including this one; page 5 is blank for your scratch work).
- Answer only in the space provided. Do not write answers on the back ola page.

Question Points Score

I. 35

2. 20

3. 45

Total 100

H He

Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar

K CaSCTiV CrMnFeCoNiCuZnGaGeASSeBrKr
RbSrY ZrNbMoTcRuRhPdAgCdInSnSbTeI Xe
CsBaLaHfTaW ReOsIrPtAuI-IgTlPbBiPOAtRn

NAME: im

la.
(5 pts) Draw 3-D Lewis structures for the two most significant resonance contńbutors of

O3 (OOO connectivity)

1b. (5 pts) Which of the following is a correct electron'dot (Lewis structure) representation of the nitrite

ion, N02- (ONO connectivity)? E

1c. (5 pts) Which of the following species ìs/are not a resonance form(s) of the anionic species in the

box? D

1d. (10 pas) Draw a single 3-Dimensional Lewis structure for the following molecule represented by a condensed formula CHBCDQOCHCHE. Be sure that the structure you draw corresponds to the major

resonance contributor.

AD ú H (91 vé

if l f’
44W“

1e. (10 pts) What is/are the product(s) of the following acid-base mechanism? Show your product(s) as Lewis structureœ).
Be sure to show the resonance structure(s) of the product(s) that would arise directly from the indicated movement of' electrons.

2a. (5 pts) Which of the following species is a resonance form of compound

LA YM

NAME:

2b. (3 pts) Identify the atomic orbitals in the C-N sigma bond in the oxime shown below? É

A)(zsp2,2sp2) B)(2Sp3,2sp3) C)(25p,2sp) D)(2sp2,2sp3) E) (25p, ls)

2c. (2 pts) Identify the atomic orbital that_ the lone pair electrons on N atom are contained in for

the oXime shown in problem 2b?

A) 2592 B) 25133 C) 23p D) 2s E) 2p

2d. (3 pts) Which of the following is the strongest base: _â

2e. (5 pts) For the following acid f base reaction which statement is true taking AG“ into

consideration? E

A) The reaction is an exothermic reaction and AG“ is zero.
B) The reaction is an endothermic reaction and AG” is negative.
C) The reaction is an exothermic reaction and AG“ is negative.

D) The reaction is an exothermic reaction and AGD is positive.
E) None of the above

2f. (2 pts) Which of these bases is thçâtrongest one which can be used (and retains its basic

character) in aqueous solution?
NAMEI

(5 pts) What is the simplest alkane, i.e., the oué with the smallest molecïlàr Weight, which possesses primary, secondary and tertiary carbon atoms?
A) 2-methy1propane B) 2-methylbutane C) 2-methylpentane D) Zl-dimethylbutane

(5 pts) The most stable conformation of lß-ethanedìol, HOCHZCHZOH, has the two hydroxyl groups qauche because:

A) this corresponds to an anti confonnation. B) in generai gauch confonnations possess the minimum energy. C) it is Stabilized by intramolecular hydrogen bondng. D) it is a staggered conformation. E) it has the highest energy of all the possible conformations.

(10 pts) Draw a Neuman projections for the least stable conformation of 3-br0mo-2- methyìpentane viewed down the C-2 t0 C-3 bond.

(10 pts) Draw a 3-D structure for the most stable conformation of the Cycîohexane derivative shown below. You need not show the hydrogen atoms for the methylene groups.

(10 pts) New draw the higher energy chair confomer of your structure in part 3e.