ngac (ttn793) – H11: Solids and Liquids – mccord – (51600) 1
This print-out should have 25 questions.
Multiple-choice questions may continue on 1. None of these
the next column or page – ﬁnd all choices
before answering. 2. armed forces.
3. intramolecular forces.
001 10.0 points
What would be the most signiﬁcant type of
intermolecular forces in a liquid sample of 4. intermolecular forces. correct
ﬂuoroform (CHF )?3
Bonds within molecules or formula units are
called intramolecular forces. Bonds between
2. hydrogen bonding particles are called intermolecular forces.
3. dispersion 003 10.0 points
What is the predominant intermolecular force
4. dipole-dipole correct between IBr molecules in liquid IBr?
5. covalent 1. ionic forces
Explanation: 2. hydrogen bonds
London forces, dispersion forces, van der
Waals or induced dipoles all describe the same
3. dispersion forces correct
intermolecular force. London forces are in-
duced, short-lived, and very weak. Molecules 4. covalent bonds
and atoms can experience London forces be-
cause they have electron clouds. London
5. dipole forces
forces result from the distortion of the elec-
tron cloud of an atom or molecule by the Explanation:
presence of nearby atoms or molecules. You might have thought that dipole forces
Permanent dipole-dipole interactions are was right. The fact is that the dipole be-
stronger than London forces and occur be- tween iodine and bromine is incredibly weak
tween polar covalent molecules due to charge -owekoacntfhettati
separation. compound is a liquid. Another FACT is that
H-bonds are a special case of very strong dispersion forces are the dominant forces here
dipole-dipole interactions. They only occur due to the SIZE of these atoms and hence
when H is bonded to small, highly electroneg- molecule. Just know that not ALL dipole
ative atoms – F, O or N only. forces are bigger than any set of dispersion
Ion-ion interactions are the strongest due to forces. Size matters, and dispersion forces
extreme charge separation and occur between win out here.
ionic molecules. They can be thought of as
both inter- and intramolecular bonding.
004 10.0 points
CHF i3 a polar molecule that does not con- Which of the following structures represents
tain H bonds; therefore, dipole-dipole forces apossiydrogenbond?
will be the most signiﬁcant type of intermolec-
ular forces present. 1. Cl H ··· Cl
002 10.0 points 2. C H ··· O
Forces between particles (atoms, molecules,
or ions) of a substance are called 3. F H ··· F correct ngac (ttn793) – H11: Solids and Liquids – mccord – (51600) 2
4. Br H ··· Br 6. 0.35 correct
H-bonds are a special case of very strong rCa=100pm rIn =72pm
dipole-dipole interactions. They only occur The energy E p , so the ratio is
when H is bonded to small, highly electroneg- r2
ative atoms – F, O or N only.
ECa |Ca |rIn |2|(72 pm)2
005 10.0 points E = 2 = |3|(100 pm)2 =0 .3456
Identify the kinds of intermolecular forces In |In|rCa
that might arise between molecules of
CH 3H. 007 (part 2 of 2) 10.0 points
Which ion will attract a water molecule more
2. London forces, dipole-dipole 1. In3+correct
3. London forces, dipole-dipole, hydrogen 2. Equal attraction
4. None of these Explanation:
The attraction of the Ca ion will be less
5. London forces than that of the In+ ion because it has both
6. hydrogen bonding
008 10.0 points
H If the interaction between two species is pro-
portionalto 1 ,whichofthefollowingislikely
H C O Hsi.r involved?
H 1. Na and H O2
006 (part 1 of 2) 10.0 points 2. ions in an ionic solid
Calculate the ratio of the potential energies 3. bromine molecules in the liquid phase
for the interaction of a water molecule with a
Ca ion (of radius 100 pm) and with an In 4. chloromethane molecules in the liquid
ion (of radius 72 pm). phase
1. 0.63 5. chloromethane molecules in the solid
3. None of these 3 ▯ E por dipole-dipole interactions.
4. 0.52 009 10.0 points
Which of the following can form intermolecu-
5. 0.76 lar hydrogen bonds? ngac (ttn793) – H11: Solids and Liquids – mccord – (51600) 3
and +3 cations will generally form hydrates.
1. PH 3 Na will also attract water due to its smaller
2. (CH ) NH correct
012 10.0 points
3. H 2O Adpouldstveaar
shape due to the property of
4. CH 3OCH 3
1. capillary action.
Only molecules with H attached to the
electronegative atoms N, O, and F can hy- 2. vapor pressure.
drogen bond. Of the molecules given only
(CH 3 2H h2s the H directly bonded to N, 3. close packing.
so it can undergo hydrogen bonding.
4. surface tension. correct
010 10.0 points
Which of the following cations is likely to be
hydrated in compounds? Explanation:
+ Molecules on the surface of a liquid are
1. Rb inﬂuenced by intermolecular attractions to-
wards the interior; these attractions pull the
2. NH +
4 surface layer toward the center. The most sta-
+ ble situation is one in which the surface area
3. K is minimal. For a given volume, a sphere has
+ the least possible surface area.
013 10.0 points
5. Li correct
Surface tension describes
+ 1. the inward forces that must be overcome
Li is the smallest.
in order to expand the surface area of a liquid