South Pasadena • AP Chemistry
Name
10 ▪ States of Matter
Period
10.1
PROBLEMS
–
Date
SOLIDS AND IMFS
1. Classify each of the following by type of solid (i.e. metallic, ionic, network covalent, or molecular), and
identify the strongest inter-particle force involved (i.e. London dispersion forces, dipole-dipole interactions,
hydrogen bonding, covalent bond, ionic bond, metallic bond).
a. NH3
Molecular Solid | HB
aa. CO
Molecular Solid | DDI
b. Kr
Molecular Solid | LDF
bb. Ar
Molecular Solid | LDF
c. HCl
Molecular Solid | DDI
cc. H2O
Molecular Solid | HB
d. F2
Molecular Solid | LDF
dd. NH4Cl Ionic Solid | Ionic Bond
e. KMnO4
Ionic Solid | Ionic Bond
ee. Brass (Cu + Al)
f.
Ionic Solid | Ionic Bond
NaCl
Metallic Solid | Metallic Bonds
g. SO2
Molecular Solid | DDI
ff. Hg
Metallic Solid | Metallic Bonds
h. CO2
Molecular Solid | LDF
gg. P4
Molecular Solid | LDF
i.
C3H8
Molecular Solid | LDF
hh. CaO
Ionic Solid | Ionic Bond
j.
CH3Cl
Molecular Solid | DDI
ii. H2
Molecular Solid | LDF
k. HF
Molecular Solid | HB
jj. Pb
Metallic Solid | Metallic Bonds
l.
Molecular Solid | LDF
kk. SF4
Molecular Solid | DDI
m. Si
Network Solid | Covalent Bonds
ll. SiC
Network Solid | Covalent Bonds
n. SiO2
Network Solid | Covalent Bonds
mm.
C6H6
PH3
Molecular Solid | LDF
o. C(graphite) Network Solid | Covalent Bonds
nn. I2
Molecular Solid | LDF
p. N2
Molecular Solid | LDF
oo. Cu
Metallic Solid | Metallic Bonds
q. CH3OH
Molecular Solid | HB
pp. K2S
Ionic Solid | Ionic Bond
r.
Metallic Solid | Metallic Bonds
Ag
s. (C2H5)2NH Molecular Solid | HB
t.
NaOH
u. Al
Ionic Solid | Ionic Bond
Metallic Solid | Metallic Bonds
v. Amalgam (Ag + Hg)
Metallic Solid | Metallic Bonds
w. PCl3
Molecular Solid | DDI
x. XeF4
Molecular Solid | LDF
y. HCN
Molecular Solid | DDI
z. Na
Metallic Solid | Metallic Bonds
2. For each of the following compounds, write the
chemical equation for the lattice energy. Then
arrange the following in increasing lattice energy:
AlN, MgO, NaF, RbI
Lowest Lattice Energy
Rb+ + I− → RbI + LE
Na+ + F− → NaF + LE
Mg2+ + O2− → MgO + LE
Al3+ + N3− → AlN + LE
Highest Lattice Energy
Compound
Boiling Pt
HF
HCl
HBr
HI
20°C
−85°C
−66°C
−34°C
3. Acetone (C3H6O) and chloroform (CHCl3) form an 5. The boiling point
unusually strong intermolecular attraction. Why is
temperatures of HF, HCl,
this? Draw a picture of how the molecules attract
HBr, and HI are shown.
each other.
a. Explain why HF has a higher BP than the
others, even though it has the lowest molecular
Cl Cl The Cl pulls electron
mass.
density away from
C−H bond, so the
It has Hydrogen bonding, which is
H
Cl
CHCl3 forms a strong
stronger than other IMFs.
CH 3
O
b. Explain why the BP temperature increases from
“hydrogen bond”-type
HCl to HI.
interaction with the O
in
C
H
O.
As the number of electrons increase, the
CH 3
3 6
electron cloud is larger and is more
4. Which of the following would be expected have a
polarizable, resulting in a stronger LDF.
higher melting point? Explain.
c.
The
boiling points of H−X compounds by
a. Cl2 or Br2
family are shown below. Make sure you can
Br2 because it has more electrons and
stronger LDF.
explain the trends of each one.
b. C4H10 or C5H12
C5H12 because it has more electrons and
stronger LDF.
c. NH3 or PH3
NH3 because it has hydrogen bonding
whereas PH3 has LDF.
d. Na or Mg
Mg because it has more electrons and
more polarizable electron cloud.
e. BeO or KCl
BeO because it has greater charges and
stronger ionic bonds.
f. ICl or Br2
ICl because it has DDI whereas Br2 has
LDF.
AP Chemistry 2001 #8
Account for each of the following observations about pairs of substances. In your answers, use appropriate
principles of chemical bonding and/or intermolecular Forces. In each part, your answer must include references to
both substances.
(a) Even though NH3 and CH4 have similar molecular masses, NH3 has a much higher normal boiling point
(–33°C) than CH4 (–164°C).
NH3 is held by hydrogen bonding, whereas CH4 is held by London Dispersion Forces. Hydrogen
bonding is stronger than London Dispersion Forces, so it takes more energy to boil NH3 than it does
to boil CH4 resulting in a higher boiling point.
(b) At 25°C and 1.0 atm, ethane (C2H6) is a gas and hexane (C6H14) is a liquid.
Both C2H6 and C6H14 have only London Dispersion Forces. Because C6H14 has more electrons and a
larger electron cloud, so they are more polarizable resulting in stronger LDFs and a higher boiling
point. With a higher boiling point, C6H14 remains a liquid at 25°C.
(c) Si melts at a much higher temperature (1,410°C) than Cl2 (–101°C).
Si is a network covalent solid held together with strong covalent bonds, while Cl2 forms a molecular
solid held by weak London Dispersion Forces. Because Covalent bonds are much stronger than
LDFs, Si has requires much more energy to melt and has a much higher melting point.
(d) MgO melts at a much higher temperature (2,852°C) than NaF (993°C).
Both are ionic solids. Because MgO (Mg2+ and O2−) has ions with greater charges than NaF (Na+
and F−), it takes more energy to break the bonds in MgO resulting in a higher melting point.