Chemistry 400
Chapter 9 Homework Problems: Ionic Bonding, Lattice Energy, Covalent Bonding and Bond Dissociation Enthalpies
1. Write out Coulomb’s Law and explain how it relates to the trends in the lattice energies of ionic compounds.
2. Write chemical reactions (don't need values) that correspond to each of the following thermochemical quantities. Be sure to include
the state of every substance (except electrons).
A. The first ionization energy of helium
B. The electron affinity of sodium
C. The enthalpy of fusion of iron
D. The crystal lattice energy of sodium sulfide
E. The bond dissociation energy of oxygen
F. The enthalpy of formation of sodium sulfide
3. Write chemical reactions (don't need values) that correspond to each of the following thermochemical quantities. Be sure to include
the state of every substance (except electrons).
A. The third ionization energy of aluminum
B. The electron affinity of oxygen
C. The enthalpy of sublimation of iron
D. The crystal lattice energy of potassium oxide
E. The bond dissociation energy of iodine
F. The enthalpy of formation of potassium oxide
4. Use the data given below to construct a Born-Haber cycle to determine the lattice energy of CaO. Show all of the reactions
written out and added up a la Hess' Law.
Reaction
Sublimation of Ca
IE1 of Ca
IE2 of Ca
BDE of O2
EA1 of O
EA2 of O
ΔH°f[CaO(s)]
ΔH°(kJ/mol)
193
590
1010
498
–141
878
–635
5. Use the data given below to construct a Born-Haber cycle to determine the lattice energy of MgF2. Show all of the reactions
written out and added up a la Hess' Law.
Reaction
Sublimation of Mg
IE1 of Mg
IE2 of Mg
BDE of F2
EA1 of F
ΔH°f[MgF2(s)]
ΔH°(kJ/mol)
148
590
1450
159
–328
–1123
6. Would you expect the crystal lattice energy of CaO to be larger or small than for MgF2? Explain.
7. Write Lewis structures for the following species. Make sure to consider formal charge, but don’t worry about resonance … yet.
A. CCl4
B. SO32–
C. SO3
D. CF2Cl2
8. Write Lewis structures for the following species. Make sure to consider formal charge, but don’t worry about resonance … yet.
A. O3
B. CH3–NH3+
C. SO3
D. CH3+
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9. Write Lewis structures for the following species. Make sure to consider formal charge, but don’t worry about resonance … yet.
A. PH3
B. CH2O
C. SO3
D. HCN
10. Write Lewis structures for the following species. Make sure to consider formal charge. Include all reasonable resonance structures
(if there are any).
A. CO32B. CH3COO–
2–
C. SO3
D. ClF5
Acids:
E. HCl
G. CH3COOH
F. HNO3
H. Weak Base: NH3
11. Write Lewis structures for the following species. Make sure to consider formal charge. Include all reasonable resonance structures
(if there are any).
A. NO3–
B. CH3COO–
–
C. ClO3
D. PF5
Acids:
E. H2SO4
F. H3O+
12. Draw a bond energy diagram (a graph of potential energy versus distance between the nuclei) for the bond in O2, which has a bond
energy of 495 kJ/mol and a bond distance of 121 pm.
13. Using the bond dissociation energy values in Tro (or in the conversion and equation sheets), calculate an approximate value of
ΔHrxn for the combustion of ethane using a one coefficient for ethane even if some of the other coefficients are fractions. Compare it
to the value obtained using ΔHf values.
14. Using the bond dissociation energy values in Tro (or in the conversion and equation sheets), calculate an approximate value of
ΔHrxn for the combustion of methane using a one coefficient for methane even if some of the other coefficients are fractions.
Compare it to the value obtained using ΔHf values.
15. Using the bond dissociation energy values in Tro (or in the conversion and equation sheets), calculate an approximate value of
ΔHrxn for the combustion of liquid acetic acid using a one coefficient for acetic acid even if some of the other coefficients are
fractions. Compare it to the value obtained using ΔHf values.
16. Using the bond dissociation energy values in Tro (or in the conversion and equation sheets), calculate an approximate value of
ΔHrxn for the combustion of ethanol using a one coefficient for ethanol even if some of the other coefficients are fractions.
17. Using the bond dissociation energy values in Tro (or in the conversion and equation sheets), calculate an approximate value of
ΔHrxn for the combustion of methanol using a one coefficient for methanol even if some of the other coefficients are fractions.
18. Using the bond dissociation energy values in Tro (or in the conversion and equation sheets), calculate an approximate value of
ΔHrxn for the combustion of phenol using a one coefficient for phenol even if some of the other coefficients are fractions.
19. Using the bond dissociation energy values in Tro (or in the conversion and equation sheets), calculate an approximate value of
ΔHrxn for the combustion of benzene using a one coefficient for benzene even if some of the other coefficients are fractions.
20. Draw skeletal structures for each of the following condensed structures.
A. CH3(CH2)6CH3
B. CH3CHCHCH3
C. (CH3CH2CH2)2NH
D. CH3(CH2)5COOH
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21. Draw the full Lewis structure (showing all bonds, atoms and lone pairs) for each of the following skeletal structures.
A.
B.
O
COOH
H2N
C.
D.
OH
OH
HO
O
HO
OH
OH
22. Some theories of aging suggest that free radicals cause certain diseases and perhaps aging in general. Free radicals are chemical
species with an odd number of valence electrons. Draw Lewis structures for each of the following free radicals listed below:
A. O2–
B. O–
C. OH
D. CH3COO (unpaired electron on terminal
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