Chemistry 101, Mid-Term Test 2
Version
B
Version B
Fall 2016
UNIVERSITY OF VICTORIA
CHEMISTRY 101
Midterm Test 2
November 18, 2016
5-6 pm (60 minutes)
Page 1 of 8
Version
B
DISPLAY YOUR STUDENT ID CARD (ONEcard) ON THE TOP OF YOUR DESK NOW
Answer all multiple choice questions on the bubble sheet provided. Use a pen (or soft
pencil). Complete the identification portion of the bubble sheet according to the example
shown, using your own name and student ID number. Indicate your Test Version (A or B)
in the line labeled ‘Form’.
Hand in only the bubble sheet at the end of the test period (60 minutes).
A DATA sheet is included, unstapled, inside the cover page of this test.
This test has 8 pages (not including the DATA sheet). Count the pages before you begin.
The basic Sharp EL510 calculator and the Sharp EL-510 RNB are the only ones approved
for use in Chemistry 101.
DO NOT BEGIN UNTIL TOLD TO DO SO BY THE INVIGILATOR
Chemistry 101, Mid-Term Test 2
Version B
Fall 2016
Page 2 of 8
This test consists entirely of multiple choice questions and is worth 25 marks. There is one mark per
question. The answers for the 25 questions must be coded on the optical sense form (bubble sheet) using a
PEN or SOFT PENCIL. Select the BEST response for each question below.
1.
Of the interhalogen compounds ICl, ICl3 and ICl5, which statement concerning their molecular dipole
moments is correct?
A.
B.
C.
D.
E.
Only ICl and ICl3 have net molecular dipoles.
All have a net molecular dipole.
Only ICl3 has a net molecular dipole.
Only ICl has a net molecular dipole.
None have a net molecular dipole.
2.
In a Valence Bond description of bonding, the molecule H3C–CH=CH2 has the following total number
of hybridized orbitals:
A. 2
B. 4
C. 6
D. 10
E. 8
3.
Which of the following statements is/are CORRECT for metallic bonding?
i)
ii)
iii)
Bonding electrons in metals are free to move from one bonding region to another.
Bonding theory for metals must include highly directional bonds as for molecules.
The energy gap (band gap) between bonding and antibonding molecular orbitals is largest for an
insulator.
There are no antibonding molecular orbitals for a semiconductor.
iv)
A. i only
B. i and ii
C. ii and iii
D. i and iii
E. ii and iv
4.
The molecular geometry (shape) of a molecule with the general formula AB2 can be:
A.
B.
C.
D.
E.
bent or linear
trigonal planar or linear
trigonal planar only
T-shaped or linear
T-shaped only
5.
Assuming that the octet rule applies to all these structures, which of the molecules: CO, HCN, HC≡CH,
has a non-zero formal charge on carbon?
A.
B.
C.
D.
E.
HC≡CH
HCN
CO
HCN and CO
none of them
Chemistry 101, Mid-Term Test 2
Version B
Fall 2016
Page 3 of 8
6.
A Lewis structure of Ibuprofen is shown below without its lone pairs of electrons. The approximate
bond angle (in degrees, °) labeled “a”, “b” and “c” in the drawing are, respectively:
A.
B.
C.
D.
E.
120, 120, 120
120, 109, 180
180, 120, 120
109, 109, 120
109, 120, 109
Carry out a VSEPR analysis of the molecule BrF5 and answer questions 7 and 8 below.
7.
The number of electron pairs (bonding and non-bonding) around the Br atom is
A.
B.
C.
D.
E.
5 bonding, 0 non-bonding
5 bonding, 1 non-bonding
6 bonding, 0 non-bonding
6 bonding, 1 non-bonding
5 bonding, 2 non-bonding
8.
How many F–Br–F bond angles are approximately 90° in BrF5?
A. 4
B. 6
C. 8
D. 0
E. 1
9. The molecular shape of the PHCl2 molecule is?
A. Bent
B. Trigonal pyramidal
C. Trigonal planar
D. T-shaped
E. Tetrahedral
Chemistry 101, Mid-Term Test 2
Version B
Fall 2016
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10. Which of the following statements about formal charges is INCORRECT?
A. In calculating formal charge, shared electrons are assigned to the more electronegative atom.
B. In calculating formal charge, unshared electrons are assigned to the atom on which they are found.
C. In general, the Lewis structure in which the atoms bear the lowest formal charges is the preferred one.
D. In general, the Lewis structure in which any negative charge resides on the more electronegative
element is the preferred one.
E. Formal charges do not represent the real charges on atoms.
11. Consider the following molecules which contain carbon-carbon bonds: ethane (C2H6), ethyne (C2H2),
benzene (C6H6) and ethene (C2H4). The correct ordering in terms of carbon-carbon bond length is: (Where A>B
means the carbon-carbon bond in A is longer than that in B.)
A. ethyne> ethene> ethane> benzene
B. ethane> benzene> ethyne>ethene
C. ethyne> ethene> ethene> ethane x ignore – announced in test
D. ethane> ethene> benzene> ethane x ignore – announced in test
E. ethane> benzene> ethene> ethyne
12. Propene, H3C–CH=CH2, has how many sigma (σ) and how many pi (π) bonds?
A. 7 σ, 1 π
B. 6 σ, 2 π
D. 3 σ, 2 π
E. 8 σ, 1 π
C. 5 σ, 3 π
Chemistry 101, Mid-Term Test 2
Version B
Fall 2016
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13. What is the molecular geometry of BrF3?
A. T-shape
B. regular tetrahedron
C. square pyramid
D. square planar
E. seesaw (irregular tetrahedron)
14. In what situation is the molecular shape the same as the shape of the electron-domain arrangement?
A. When all but one of the electron pairs on the central atom are involved in bonding.
B. When the central atom obeys the octet rule.
C. When all of the electron pairs on the central atom are involved in bonding
D. When the central atom does not obey the octet rule.
E. More than one of the above are correct.
15. How many equivalent resonance structures (having the minimum number of formal charges) are possible
for the ion (SFO3)− ? (The central atom is S.)
A. 5
16.
B. 4
C. 3
D. 2
E. 1
What is the orbital hybridization assigned to the two C atoms and the O atom in the molecule below, in
order from left to right?
O=C=CH2 ?
A. sp2, sp, sp3
B. sp3, sp, sp2
C. sp2, sp2, sp2
D. sp2, sp, sp
E. sp2, sp, sp2
Chemistry 101, Mid-Term Test 2
Version B
Fall 2016
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17. Using bond enthalpies (given as Average Bond Energies in the Data Sheet) estimate the enthalpy change
(ΔH, heat of reaction) for the following gas-phase reaction.
(The bond energy value for S−C is 259 kJ mol-1 and that for S−H is 339 kJ mol-1.)
HS
CH2CH2
A. +160 kJ mol–1
18.
+ 2 HF
SH
B. 0 kJ mol–1
F
C. –824 kJ mol–1
CH2CH2
+ 2 HSH .
F
D. –160 kJ mol–1
E. +824 kJ mol–1
Consider the following three molecules. Which molecule(s) is(are) polar? (That is, which molecules
have a non-zero net molecular dipole moment µ?)
BF3
A. NF3 only
B. BF3 only
NF3
CF4
C. CF4 only
D. both BF3 and NF3
E. none of them
19. Which of the following statements is INCORRECT?
A.
The bonding in a linear arrangement of electron domains can often be rationalized using sp hybrid
orbitals.
B.
When assigning the orbital hybridization, only bonding electrons are considered, since lone pairs do not
participate in hybridization.
C.
In the molecule H2C=O the H−C−O bond angles are slightly greater than 120°.
D.
Double bonds take up more space than single bonds.
E.
In NF3 there are bond angles that are slightly less than the regular tetrahedral angle of 109.5°.
Chemistry 101, Mid-Term Test 2
Version B
Fall 2016
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20. Consider the following molecular orbital energy diagram, which applies to diatomic species
that use only 1s orbitals.
molecular
orbitals
atomic
orbital
atomic
orbital
The MO diagram shown above can represent the electron energy levels for which of the following real or
hypothetical molecule(s) or ion(s)?
i.
H2–
A.
ii.
i only
He2+
iii.
B. ii only
He2–
iv.
C. iv only
HHe
v.
D. ii, iii and iv
H2
E. i, ii and iv
21. Which one of the following resonance structures of nitrous oxide (N2O) represents the most significant
contributor to the resonance hybrid in this neutral molecule?
A.
B.
C.
22. Which property is NOT a characteristic of most ionic liquids?
A.
B.
C.
D.
E.
Polyatomic cations and anions
Non-flammable
Ordered phase above the melting point
Mismatch of size/shape of anion and cation
Non-volatile
D.
E.
Chemistry 101, Mid-Term Test 2
23.
Version B
Fall 2016
Page 8 of 8
Which of the sketches below best depicts a nematic liquid crystal phase?
A.
B.
C.
D.
E. none of them
24. Which ONE of the following pairs of molecule and intermolecular force is CORRECT?
A. O=C=O, only London dispersion forces
B. H2S, only London dispersion
C. Ethene (C2H4), dipole-dipole.
D. NCl3, only London dispersion
E. CH3CH2NH2, only dipole-dipole
25. Tungsten (W) has the highest melting point of all the pure metals (3422 °C). Using your knowledge of
metallic bonding, choose the best explanation for this fact from the selection below.
A. Tungsten has a large first ionization energy, so it will not form an ionic lattice.
B. Tungsten’s molecular orbitals form a continuous band.
C. Tungsten has a half-filled s-d molecular orbital band, so the bonding between atoms is of maximum
strength.
D. Tungsten has as many anti-bonding electrons as bonding electrons, so the bonding between atoms is
of maximum strength.
E. Tungsten has electrons in the 5d subshell.
END