More Practice With IM
1. What type of crystal will each of the following substances form in its solid state? Choices
to consider are metallic, ionic, covalent, or molecular crystals.
(a) C2H6 __________
(b) Na2O ____________ (c) SiO2 ______________
(d) CO2 ______________ (e) N2O5 __________ (f) NaNO3 ______________
(g) Al ________________ (h) C(diamond) ______ (I) SO2 ________________
__________________________________________________________________________
_______
2. Circle all the compounds in the following list which would be expected to form
intermolecular hydrogen bonds in the liquid state:
(a) CH3OCH3
(b) CH4
(c) HF
(d) CH3CO2H
(e) Br2
(f) CH3OH
(dimethyl ether)
(acetic acid)
(methanol)
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_______
3. Specify the predominant intermolecular force involved for each substance in the space
immediately following the substance. Then in the last column, indicate which member of the
pair you would expect to have the higher boiling point.
Predominant
Predominant
Substance with
Substance
Intermolecular
Substance
Intermolecular
Higher Boiling
#1
Force
#2
Force
Point
(a) HCl(g)
I2
(b) CH3F
CH3OH
(c) H2O
H2S
(d) SiO2
SO2
(e) Fe
Kr
(f) CH3OH
CuO
(g) NH3
CH4
(h) HCl(g)
NaCl
(i) SiC
Cu
Predicting Molecular Geometry and Hybridization
1. In each case, predict (a) the approximate bond angle(s), (b) the hybridization around the
underlined atom. (Note: It is helpful to first sketch the Lewis stucture!)
Molecule or Ion
(1) OF2
(2) H2CO
(3) NO2+
(4) BF3
(5) SbF5
(a) No. of valence
e - ‘s
(b) Lewis structure
(c) Approximate
bond angle(s)
(d) Hybridization
(e) Polar or nonpolar molecule?
(f) Geometry name
Ion: Not
applicable
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____
2. For each of the molecules below fill in the indicated items in the chart. The central atoms
are underlined.
Molecule
(1) SO2 (2) HBF2
(3) XeF4
(4) CH2Cl2
(5) NF3
(a) No. of valence
e - ‘s
(b) Lewis structure
(c) Approximate
bond angle(s)
(d) Hybridization
(e) Polar or nonpolar molecule?
(f) Geometry name
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__
3. Predict (a) the approximate bond angle, (b) the hybridization around the indicated atoms
(the atoms to which the arrows are drawn in the structures below). Write your answers near
the corresponding labels (1 to 5) in the drawings. (Note: the lone pairs on the F atoms are
omitted.)
H
H
N
1
F
S
F
F
F
2
F
Br
F
4
C
N
F
3
C
N
F
F
5
C
H
C
C
N
O
H
N
H
Intermolecular Forces Worksheet
Fill in the Blank:
Terms: bonds, charges, dipole, forces, dipole-dipole forces, hydrogen bonding, ions, ionic,
London dispersion forces, unchanged, unequal
1. When a molecular substance changes state (ex: from liquid to gas), the atoms within the
molecules are
2. No are broken when a molecular substance changes state.
3. The forces holding together in solids are ionic
electrostatic forces. Opposite charges attract each other. These are the strongest intraparticle
.
4. The strongest intermolecular forces in a sample of oxygen gas are the
5. sharing of electrons in a molecule results in the formation of
partial on the molecule.
6. A occurs because one part of a molecule has a partial positive charge while
another part of a molecule has a partial negative charge.
7. There are 3 intermolecular forces present in a sample of water. List the 3 intermolecular
forces in order of strength from strongest to weakest:
Intermolecular Forces Worksheet 4
Page 1 of 2
1. Classify each of the following as ionic, molecular (polar or non-polar), network covalent, or
metallic.
(A) sodium
(B) SiO2
(C) C10H8
(D) CaCO3
(E) titanium
(F) fluorine
2. Of the four general types of solids, which one(s)
(A) melt below 100°C to give a non-conducting liquid?
(B) melt at moderate (l00 - 600°C) temperatures to give a conducting liquid?
(C) melt at very high temperatures to give a conducting liquid?
(D) conduct electricity as a solid?
(E) are very hard solids but dissolve readily in H2O?
(F) are very hard solids that do not dissolve in common solvents?
(G) dissolve in non- polar solvents?
3. For each pair below choose the compound with stronger intermolecular forces and identify
the forces
involved.
(A) ICl or NaCl
(B) Kr or Ar
(C) H2Te or H2S
(D) H2S or H2O
(E) SiC or LiCl
(F) CO2 or SiO2
(G) GeH4 or AsH3
(H) CCl4 or CH4
©1994–PTAS, Inc.
Intermolecular Forces Worksheet 4
4. Substance Melting Point, K Substance Melting Point, K
N2 63.3 Kl 854.15
C2H6 89.85 NaF 1266.15
HCl 158.4 SiC > 2,273
(A) In terms of the types of attractive forces and/or bonds in the above substances, explain
the trend
in the melting points.
(B) For pairs of substances with the same predominate attractive forces and/or bonds ,
discuss the
factors that cause variations in the strengths of the forces and/or bonds.
5. The molecular weights of butane, chloroethane, acetone, and 1-propanol are approximately
the same.
Boiling point and solubility in water data are listed in the table below.
Compound Formula Boiling Point, K Solubility in Water
Propane CH3—CH2—CH3 231 Insoluble
Fluoroethane CH3CH2—F 235 Insoluble
Dimethyl ether CH3OCH3 248 Completely miscible
Ethanol CH3—CH2OH 352 Completely miscible
In terms of molecular polarities (dipole moments) and/or hydrogen bonding, explain in a
qualitative
way the differences in the
(A) boiling points of propane and fluoroethane
(B) water solubilities of fluoroethane and dimethyl ether
(C) water solubilities of propane and ethanol
(D) boiling points of dimethyl ether and ethanol
Answers:
1. (a) molecular; (b) ionic; (c) covalent (network solid); (d) molecular; (e) molecular; (f) ionic;
(g) metallic; (h) covalent (network solid); (i) molecular.
2. Hint: Molecule must contain H bonded to O, N, or F, since only H bonded to O, N, or F
can form a hydrogen bond with an O, N, or F on another molecule. Thus (c), (d), and (f)
should be circled.
3. Hint: Choices for the predominant intermolecular force are metallic bonding, ionic
bonding, network covalent bonding, hydrogen bonding, and dispersion forces (induced dipole
– induced dipole forces). Dipole-dipole forces are generally dominated by dispersion forces
and are rarely predominant.
(a) dispersion forces; dispersion forces; I2.
(b) dispersion forces; hydrogen bonding; CH3OH.
(c) hydrogen bonding; dispersion forces; H2O.
(d) network covalent bonding; dispersion forces; SiO2.
(e) metallic bonding; dispersion forces; Fe.
(f) hydrogen bonding; ionic bonding; CuO.
(g) hydrogen bonding dispersion forces; NH3.
(h) dispersion forces; ionic bonding; NaCl.
(i) network covalent bonding; metallic bonding; SiC.