Chapter 11: Intermolecular Forces
1. What type of intermolecular forces do the following compounds contain?
a.BF 3
-dispersion forces
b. AsF 5
-dispersion forces
c. HCN
-dipole forces
-dispersion forces
d.TeF 5 -Ion forces
-dipole forces
-dispersion forces
e. CCl 4
-dispersion forces
2. What types of intermolecular forces exist between the following compound pairs?
a. LiF and CH 4
-dispersion forces
-dipole-induced dipole force
b. SO 2 and I 2
-dispersion forces
-dipole-induced dipole forces
c. NH 4 + and H 2 S
-dispersion forces
-Hydrogen bonding
-ion-dipole forces
d. F- and H 2 O
-dispersion forces
-Hydrogen bonding
-Ion-dipole forces
e. Mg2+ and AsF 5
-Dispersion Forces
-Ion-induced dipole forces
f. HCN and NH 3
-Dispersion forces
-Dipole-Dipole Forces
g. BF 3 and H 2
-Dispersion forces
3. Indicate which in the following pair has the higher melting point:
a. HgS or HgCl
-HgCl
b. KCl or KI
-KI
c. HCl or F 2
-HCl
d. SiH 4 or H 2 S
-H 2 S
e. H 2 O or H 2 S
-H 2 O
f. H 2 S or H 2 Se
-H 2 Se
4. X rays of wavelength 0.154 nm are diffracted from a crystal at an angle of 14.17O. Assuming that
n=1 calculate the distance (in pm) between the layers in the crystal.
Convert to picometers
0.154 nm (1000 pm/1nm) = 154 pm
Plug in given values to Equation:
2 d sinθ = nλ
d = nλ/ 2 sinθ
d=(1)(154 pm)/ (2 sin(14.17))
d=314 pm
5. The distance between layers in a NaCl crystal is 282 pm. X rays are diffracted from these layers
at an angle of 23.0O. Assuming n= 1 calculate the wavelength of the X rays in nm.
Rarrange the equation and plug in given values:
2 dsinθ= nλ
λ= 2 d sinθ/ n
λ= 2 (282 pm) sin (23.0 O) / 1
λ = 220 pm
Convert pm to nm:
220 pm (1 nm/1000pm) = 0.220 nm
6. What type of crystalline solid do the following compounds create?
a. NaCl
-ionic
b.CH 3 F
-molecular
c. Fe
-metallic
d. NH 3
-Molecular
e. I 2
-covalent
f. H 2 S
-Molecular
g. CuO
-Ionic
h. Cu
-Metallic
i. SiO 2
-covalent
j. HF
-Molecular
k. Hg
-Metallic
l. CH 4
-Covalent