Hour Exam I
Fall 2011
Name:
10-6-2011
PLEASE READ:
This practice exam is based on last year’s Chem 202 exam #1. I have highlighted those questions
that I will not ask you on this exam (but you should definitely try to do them on your own), but
instead, I will have 2-3 questions from the Fundamental Sections that deals with stoichiometric
type calculations (i.e. limiting reagent, empirical/molecular formula, % yield, molarity, etc.)
*Make sure you download the hint page (located on the Exam Info page of our course website) to
help you work on the practice exam
Name: _____________________
Chem 202
Hour Exam I, Oct. 6 2011
Prof. Gruebele
Instruction Page
Signature: __________________
Quiz Sect: ______
TA: _______________________
Instructions:
Do not open this booklet or begin the exam until you are told to do so; in the meantime, fill
in the information requested below.
This midterm contains 25 multiple-choice questions (4 pts. each). Fill in your name, signature,
quiz section and TA name above. On the bubble answer sheet fill in the same information;
use the two digits of your quiz section under "class" (e.g. section “AQ4”). Failure to fill in all
information may delay grading of your exam. With your signature, you pledge that the answers
you provide are obtained with no aid but this exam booklet and a calculator.
You may write on any part of the exam. However, only bubbles filled in on the answer sheet
will count for credit.
The exam booklet will be returned to you during quiz section; circle your answers on it if you
want a personal record (bubble sheets will NOT be returned).
Exam time: 1 hour; there are 4 pages of questions. Times will be noted on the
board.
Refer to the hint sheet for any equations or numbers not given in the questions that
you might need.
1
Hour Exam I
Fall 2011
Name:
10-6-2011
1) An electron in a plasma TV display screen is moving freely at a velocity of 5000
m/s. What is its kinetic energy in Joules?
a) 2.2.10-18
b) 3.3.10-30
c) 4.1.10-20 d) 2.2.10-23
e) 1.1.10-23
Who says beans don’t have an immune system? Identify the numbered hybridized
atoms in wyerone acid, which beans use to kill attacking fungus.
2) a) sp
b) sp2
c) sp3
3) a) sp
b) sp2
c) sp3
4) a) sp
b) sp2
c) sp3
5) The degeneracy of the first excited state of a particle in a cubic box of either
one, two or three dimensions is: [Hint: cubic means all lengths L are equal.]
a) 1, 2, 3
b) 1, 1, 1
c) 0, 0, 0
d) 1, 2, 2
e) 3, 3, 3
6) What is the longest wavelength of a photon that will still ionize a Lithium atom?
a) 15.7 nm
b) 157 nm
c) 0.004 m
d) 230 nm
e) 400 nm
7) Which of the following is the x-p plot for the lowest energy state of a spring
allowed by the Heisenberg principle?
8) The Balmer series of a hydrogen atom is a series of sharp emission lines that
ends in the n=2 state. The longest wavelength line is called Balmer-α. What color
is this line? [Hint: emitted color is the same as absorbed color.]
a) UV
b) blue-green
c) yellow
2
d) red
e) IR=infrared
Hour Exam I
Fall 2011
Name:
10-6-2011
9) What is the effective nuclear charge of magnesium and, given the IP (same as
IE) of similar atoms on the hint page, what is its ionization potential (energy) in
kJ/mole?
a) 1, 942
b) 1.5, 738
c) 1.5, 942
d) 2, 738
e) 2, 942
10) A 4p orbital (n=4, ℓ=1) has how many nodes? (planar = angular is a “flat”
node, radial is a “spherical” node)
a) 1 radial, 2 planar
d) 2 radial
b) 3 radial, 1 planar
e) 2 radial, 1 planar
c) 1 radial, 1 planar
11) What is the valence e- configuration of iron, the most stable nucleus in the
universe?
a) 4s23d7
b) 4s13d7
c) 4s23d6
d) 3s23d7
e) 3s13d7
12) Two methyl radicals are coming together to make a chemical
bond and form ethane. The potential energy as a function of the
C to C bond distance looks like.
c)
b)
a)
0
R
V(θ)
V(θ)
V(θ)
V(θ)
R
0
d)
R
0
0
R
13) Based on electronegativities, which of the following uncharged molecules has
incorrectly assigned partial charge(s) δ?
δ+ /2
δ+/2 δ- δ+ /2
δ- H
a) O
b)
O=S=O
H
δ+ /2
6δ+
δ+ δc) I-Br
3
δ- F
δ
F
δd) F-S-F δδ- F F δ-
e) a and d
Hour Exam I
Fall 2011
Name:
10-6-2011
14) Using MO theory, the bond order and magnetism of the charged molecule
ArH+, common in the upper atmosphere of the Earth, is
a) 1, paramagnetic
b) 0.5, diamagnetic
c) 0.5, paramagnetic
d) 1, diamagnetic
e) 1.5, paramagnetic
15) When you fill electrons into the MO diagram of the N2 molecule, the lowest
unoccupied MO looks like:
a)
b)
c)
d)
e)
16) Ozone is a dangerous pollutant at low altitude, but an important UV screen in
the upper atmosphere. Which Lewis dot structure is closest to the actual
wavefunction of Ozone?
17) Phosphene (PH3) is a toxic gas used in the manufacture of n-doped
semiconductors chips. All H-P-H bond angles are 93°. To a first approximation,
which atomic/hybrid orbitals on phosphorous best describe the bonding in the
localized electron picture?
18) Two electrons fill into energy levels as shown to make the
lowest energy state. Which of the following is definitely true:
a) This must be an excited state, could never be the lowest state
b) This is close to the lowest energy state, but the upper e- should be flipped
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Hour Exam I
Fall 2011
Name:
10-6-2011
c) If ∆E is small, Pauli exclusion minimizes e- repulsion, making it the lowest state
d) This violates the Pauli exclusion principle because both e- have the same spin
e) If ∆E is large, the upper e- should be moved down without flipping.
19) What is the electron affinity of O+ atomic ion?
a) 1402
b) 1314
d) The same as O atom
c) 1682
e) insufficient information on hint page
20) Ψpx ~ sinθ cosφ. Ψpy ~ sinθ sinφ. Ψpz ~ cos θ. An electron is in the triply
degenerate p state, nothing further specified. The probability P(θ, φ) of finding the
electron at angles θ and φ is
a) sinθ (sinφ + cosφ)
d) independent of θ
b) independent of φ
e) sin2θ sinφ cosφ
c) independent of θ and φ
21) A single potassium atom is inside the cavity of a C60 molecule (cavity diameter
7 Å) in the lowest possible energy state. What is the velocity spread?
a) 0
b) 15 m/s
c) 1500 m/s
e) K does not fit inside a C60 cavity
d) ª
1
15
c
22) Which particle has greater momentum?
a) An electron moving at 5000 m/s
b) An X-ray photon of 0.5 nm wavelength
23) The molecule trans-hexatriene =
acts as a box for electrons
because of the conjugated pi electrons. Assuming the particle in a box model for
the pi electrons, and knowing the lowest energy photon that can be absorbed has
frequency 1.2.1015 Hz, you estimate the size of the hexatriene ‘box’ to be:
a) < 2 Å
b) 2 to 4 Å
c) 4 to 6 Å
5
d) 6 to 8 Å
e) >8 Å
Hour Exam I
Fall 2011
Name:
10-6-2011
24) Which of the following orbitals do not have the right symmetry to make a
bonding or antibonding combination when the orbitals are brought together along
the dotted line?
a)
b)
c)
d)
e)
25)
Ψ
Ψ
Ψ
1)
2)
x
x
x
Ψ
Ψ
4)
3)
x
5)
x
Which wavefunction above best matches the orbital formula Ψ~ (2-r/a) e-r/a ?
a) 4, 2s
b) 2, 1s
c) 5, 2s
d) 3, 3px
e) 1, 3px
That’s it, folks!
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