Answers to Quiz

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Answers to Quiz 1
Note Although the quiz did not ask for
explanations, make sure you know them for your
exams.
1. Name the 3 intermolecular forces
Dipole forces London forces Hydrogen bonding
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2. Draw 3 Lewis structures of water and indicate
exactly where the intermolecular forces are
located.
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3. Which has the higher boiling point? A. HCl
B. HF Ans. HF because it has H-bonding.
HCl has only dipole forces.
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4. Which has a permanent dipole? A. CH3OCH3
B. CH3NCH3 CH3 C. both D.
neither. Ans. Both because both are polar
molecules. Note that CH3OCH3 is not a linear
molecule.
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A. CH3OCH3 B. CH3NCH3
CH3
Molecular Geometry BENT
TRIGONAL PYRAMIDAL Both molecules are polar
and therefore have permanent dipoles.
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5. Which has the higher viscosity? A.
B.
Ans. B has a larger surface for interaction with
neighboring molecules and there has stronger IMF
(London forces) than A, which is more compact.
A stronger IMF means the molecules will hold on
tighter to each other and not flow as easily.
Thus, B has the higher viscosity.
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6. Which has a higher surface tension?
A. B.
B. is more compact and therefore has lower IMF.
It has the lower surface tension. Ans. is A,
which provides more contact area for IMF.
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7. Which has the higher boiling point?
A. LiCl B. F2
LiCl is an ionic compound with very strong ionic
bonds. F2 is a nonpolar molecule with only weak
London forces. Compounds with strong IMF have
high boiling points. Ans. A
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8. when KBr is dissolved in methanol what is the
force that allows it to dissolve?
Ans. ion-dipole force Methanol is a polar
compound. C-O and O-H are polar bonds. K is
attracted to the ?- of O and Br- is attracted to
? of H.
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Bonus Examine the structure of soap shown below.
Explain in full sentences why you might expect
it to dissolve both in water and in grease.
One hydrocarbon end of the molecule is nonpolar
and would dissolve in the nonpolar grease. The
other (carboxylate) end is ionic and would
dissolve in the water. Note Just saying it is a
surfactant does not answer the question. You only
gave a name to it instead of providing an
explanation.
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