Name: _____KEY________________
CHEM&142_EXAM 1_SPRING 2009_CHAPTERS 20 & 11_100 POINTS
Important equations and values on the last page
1. _F__ T/F The greater the IMF of a substance, the greater its vapor pressure. (3
points)
2. _T__T/F The below forms a nonsuperimposable mirror image; i.e., a chiral
molecule: (3 points)
F
I
C
Br
H
3. In each pair circle the best choice (3 points each – 12 points total)
a. Lower melting point: propane vs. ethanol
b. Greater surface tension: 1,2-ethane-diol vs. water
c. Lower viscosity: water vs. methanol
d. Greater volatility: methanal vs. methane
4. ___________ typically have a horrid smell similar to wet goat and fetid sweat. (4
points)
a. Carboxylic acids
b. Cycloalkanes
c. Ethers
d. Esters
5. Geometric isomers have the same: (4 points)
a. Structure
b. Number and type of atoms
c. None of the above
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6. Pick one of the below that correctly describes the packing efficiency of the unit
cell from least to greatest. (4 points)
a. FCC<BCC<SC
b. FCC<SC<BCC
c. SC<FCC<BCC
d. SC<BCC<FCC
7. According to the phase diagram of sulfur above, there is/are ________ critical
temperature/pressure point(s). (4 points)
a. One
b. Two
8. If monoclinic sulfur is held at a constant pressure of 0.10 mm Hg and the
temperature is steadily decreased to 5C, it will (4 points)
a. Condense
b. Melt
c. Sublimate
d. None of the above
9. List four unique characteristics of water due to hydrogen bonding: (4 points)
HIGH SURFACE TENSION, SPECIFIC HEAT CAPACITY, M.P., AND B.P
CAPILLARY ACTION, LIQUID PHASE DENSER THAN SOLID PHASE
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10. Why can’t water striders walk on oil? (4 points)
NO H-BONDING TO YIELD HIGH SURFACE TENSION
11. Explain why nitrogen is more soluble in water than oxygen. (4 points)
NITROGEN ATOMS ARE LARGER THAN OXYGEN ATOMS AND THIS
CAUSES A GREATER POLARIZABILITYIN THE FORMER SPECIES
12. Name the following molecules: (5 points each – 10 points total)
a.
4-ETHYL-3-METHYLOCTANE
O
O
b.
METHYL HEPTANOATE
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13. Draw the skeleton structure for the following molecules: (5 points each – 10
points total)
a. Diisopropyl ether
O
b. 3-ethylbenzoic acid
O
OH
14. Draw the skeletal structures and name the two geometric isomers of 2-hexene: (5
points each – 10 points total)
cis-2-hexene
trans-2-hexene
15. Crystalline silicon has a cubic structure. The unit cell edge length is 543 pm. The
density of the solid is 2.33g/cm3. Calculate the number of silicon atoms in one
unit cell. (MW = 28.0856 g/mol) (10 points)
6.022 1023 atoms (543 1010 cm)3 2.33g
mol
atoms



 8.00
3
mol
u.cell
cm
28.0856 g
u.cell
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16. Argon crystallized in the FCC arrangement at 40 K. Given that the atomic radius
of Ar is 191 pm, calculate the density of solid Ar. (MW = 39.948g/mol) (10
points)
FCC: ( 8) r = x = ( 8) 191pm = 540. pm= 540. 10-10 cm
39.948g
u.cell
mol
4atoms



 1.69 g 3
-10
3
23
cm
mol
(540. 10 cm) 6.022 10 atoms u.cell
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SC: x = 2r
BCC: x = 4r/3
FCC: x = (8)r
H vap
1
C
R
T
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