Chemistry 110
Exam 2, 8:00 Section
G. E. Rodgers
(There are 130 points on this exam.)
November 7, 2003
Name _________________________________
Honor code: ____________________________
(30 pts) I. Multiple Choice: Circle the letter corresponding to best answer. Choice: Answer 10 of the
following 12 items. That is, you can omit answering two of these without penalty. Put an
asterisk next to the items you wish not to be graded.
1. Which of these unconventional “chemical” terms has Dr. Rodgers used in class?
(a) p-orbitals are “pointier” than s-orbitals
(b) lone pairs are “scarier” than bonding pairs
(c) formal charges can be “psyched out” easier than they can be calculated.
(d) the horizontal trends in ionization energy are “kinky”
(e) some parts of chemistry can best describe by “quick and dirty” theories.
(f) when describing hybrid orbitals, don’t worry about “de tails”.
(g) “when in doubt – hybridize!”
(h) some electrons can be represented by “little houses with smoke coming out their
chimneys”.
(i) all of the above*
2. In our green KaFeb(C2O4)c  dH2O compound, the oxalate anion is the
(a) loose base
(e) Erroneous base
(b) loose cannon
(f) Bronchial base
(c) Lewis base
(g) Lewis acid
(d) Clark base
(h) none of these
3. Using Lewis structures with the most favorable formal charges, the average bond order of
the S-O bonds in the sulfate ion is
(a) 0.25
(b) 1.00
(c) 1.25
(d) 1.33
(e) 1.50
(f) 1.75
(g) 2.00
4. Of NaCl, KCl, CaO, and MgO, the salt with the greatest magnitude of lattice energy is
(a) NaCl
(b) KCl
(c) CaO
(d) MgO
(e) not enough information to tell
5. The proper name of Fe2(SeO3)3 is
(a) iron(II) selenate
(b) iron(III) selenite
(d) iron(III) selenate (e) iron(III) hyposelenite
(c) diiron trioxoselenate
(f) none of these
6. The best name for HI(aq) is
(a) hydrogen iodide
(d) hydroiodous acid
(b) hydrogen iodate
(e) hydrohypoiodous acid
(c) hydroiodic acid
(f) none of these
*Let’s face it – he has used all these silly words and phrases. He’s hopeless! How did he ever
get tenure in the sophisticated Allegheny College chemistry department?
Exam 2, Chemistry 110, Fall 2003
Page 2 of 5
7. Which compound has bonds of the least polarity?
(a) CaO
(b) CO
(c) NO
(d) PoO
(e) not enough information to tell
8. Which of the following polyatomic ions contains the shortest Cl-O bonds?
(a) hypochlorite
(b) chlorite
(c) chlorate
(d) perchlorate
9. Which of the following molecules are non-polar?
(a) AlCl3
(b) NCl3
(c) ClF3
(d) none are polar
(e) all are polar
10. The T-shaped structure corresponds to which of the following VSEPR designations?
(a) AX3
(b) AX3E
(c) AX3E2
(d) AX3E3
(e) AX4E
11. Which of the following has the smallest ionic radius?
(a) S2-
(b) Cl1-
(c) P3-
(d) K1+
(e) impossible to tell
12. The hybridization of the underlined atom in bold type in H2N-CH2-COOH is
(b) sp2
(a) sp
(c) sp3
(d) sp3d
(e) sp3d2
(10 pts) II. Judging Resonance Structures Revisited: Of the following resonance structures for the
phosphate ion, which is the most favorable, that is, which would be of the lowest energy?
Carefully explain your answer.
(a)
(7 pts)
O
 3- (b)
O
 3-
(c)
O
 3-
(d)
O
 3-
O– P –O
O– P =O
O= P =O
O=P =O
O
O
O
O
(e)
O
 3-
O=P =O
O
III. Redox Equation: Balance the following skeletal equation:
Ce4+ + NO21- + H2O  Ce3+ + NO31- + H+
Which reactant is the reducing agent? Assign oxidation numbers to explain your answer.
Exam 2, Chemistry 110, Fall 2003
Page 3 of 5
(13 pts) IV. Lewis Structures Revisited: Provide Lewis structures for the following molecules, salts,
or ions.
1. SnCl2
2. NaClO2
3. HClO3
(13 pts) V. Mass Percentages and Formulas: A compound is 54.4% by mass iodine and 45.6%
chlorine. Determine its empirical formula, name the compound, and determine its molecular
geometry by drawing a diagram and giving it a descriptive name such as “linear”, “trigonal
planar”, etc. Show all of your work as clearly as possible.
(16 pts) VI. A Representative –ic Acid in All Its Glory! Draw Lewis, VSEPR, and VBT diagrams of
nitric acid. Assign formal charges in the Lewis structure, estimate the value of bond angles in
the VSEPR diagram, and label all orbitals and bonds in the VBT diagram. If there are
resonance structures, use one of these in the VBT section of your answer.
Lewis
VSEPR
VBT
Exam 2, Chemistry 110, Fall 2003
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VII. The Return of the Natives!
(12 pts) 1. Draw the abbreviated box-like or orbital diagrams for oxygen and fluorine. What native
atomic orbitals would these atoms use to form oxygen difluoride, OF2? Under these
circumstances, what would be the value of the F-O-F bond angle in this molecule? Explain
your answer. Would the bonds be equivalent? Why or why not?
(7 pts)
2. Draw a diagram showing the best valence bond picture of OF2. Carefully label all orbitals
and types of bonds in your diagram.
(10 pts) VIII. Studying by Writing, Part A. Answer one of the following two questions. Do not
answer both. Circle the number corresponding to the question you wish to answer.
1. Carefully define promotion energy and bond energy. Under what circumstances is
promotion energy worth spending? Why? Give a specific example as part of your
answer.
2. Carefully define lattice energy. Why is it an important consideration in the formation
of ionic compounds? Give a specific example as part of your answer.
Exam 2, Chemistry 110, Fall 2003
Page 5 of 5
(12 pts) IX. Studying by Writing, Part B. Carefully define the terms “native atomic orbitals” and
“hybrid orbitals”. Why must so many molecules be described using hybrid rather than native
atomic orbitals? As part of your essay, give at least two specific examples not otherwise found
in this exam that illustrate your point.