CHEM 200/202 Fall 2016
CHEM _______
Exam 3-A
November, 19 2016
Lab Section Number: _____
Name (printed):_____________________________________________
Signature:______________________________________
This exam consists of 36 questions all of equal value for a total of 225 points.
Make sure that your test has all of the pages. Please read each problem
carefully. There are no intentionally misleading questions; each problem
should be taken at its face value. Please mark your answers on the Scantron
sheet provided to you and on the actual exam.
You will be given a periodic table and an exam information sheet to use
during the exam. You may remove it from the exam make it more accessible.
You may also use the designated Casio fx-300ms-plus calculator or
equivalent non-programmable non-graphing scientific calculator during the
exam. Use the back pages of the test as scratch paper. You are not allowed to
use any devices capable of accessing the internet, textbooks, notes, or
homemade reference sheets during the exam.
You may leave if you finish the exam early. Give the exam and the
information sheet to your TA and leave quietly without disturbing other
students. Before leaving, check that all your answers have been properly
entered on the Scantron sheet and the exam and that your name is written on
every page of the exam and on the Scantron sheet.
All cell phones and electronic devices must be turned off and put away.
Please remove all hats and caps. Place your books and all papers out of sight
under your seat. If the TA believes that you might be looking at your
neighbor’s paper, you will be asked to move to a new location.
Exam scores will be posted on Blackboard as soon as the grading is
complete. Your test will be returned to you in the first lab meeting of next
week. If you have any questions regarding the grading of your exam, please
notify your TA.
The time available for the exam is 120 minutes. Good luck!
1 of 9
CHEM 200/202 Fall 2016
Exam 3-A
Name: ___________________________________________
November, 19 2016
Lab Section #: _______
Please mark your answers on the scantron sheet using a #2 pencil and also mark your answers
on the exam itself.
Mark Test From “A” on your scantron.
1. Arrange the following bonds in order of increasing bond strength.
(a)
(b)
(c)
(d)
(e)
C–I < C–Br < C–Cl < C–F
C–F < C–Cl < C–Br < C–I
C–Br < C–I < C–Cl < C–F
C–I < C–Br < C–F< C–Cl
None of the above orders is correct.
2. Which of the following is the most electronegative?
(a)
(b)
(c)
(d)
(e)
Na
Ru
Si
Te
S
3. Arrange aluminum, boron, nitrogen and phosphorus in order of increasing electronegativity.
(a)
(b)
(c)
(d)
(e)
Al < B < P < N
B < Al < N < P
Al < N < P <B
N < P < B < Al
None of the above orders is correct.
4. Arrange oxygen, sulfur, calcium, rubidium, and potassium in order of decreasing
electronegativity.
(a)
(b)
(c)
(d)
(e)
O > S > Ca > Rb > K
O > S > Ca > K > Rb
O > S > Rb > K > Ca
O > S > Rb > Ca > K
None of the above orders is correct.
5. Which of the following displays the greatest ionic character in its bonds?
(a)
(b)
(c)
(d)
(e)
NO2
CO2
H 2O
HF
NH3
2 of 9
CHEM 200/202 Fall 2016
Exam 3-A
November, 19 2016
6. Which of the following contains covalent bonds?
(a)
(b)
(c)
(d)
(e)
MgF2
NaCl
IBr
LiBr
Cu
7. Select the compound with the highest lattice energy
(a)
(b)
(c)
(d)
(e)
BaO
NaI
LiBr
MgO
CaS
8. The lattice energy of MgCl2 is the energy change for which one of the following processes?
(a)
(b)
(c)
(d)
(e)
MgCl2(s) → Mg(s) + Cl2(g)
MgCl2(s) → Mg(g) + 2Cl(g)
MgCl2(g) → Mg2+(s) + 2Cl–(g)
MgCl2(s) → Mg2+(g) + 2Cl–(g)
MgCl2(aq) → MgCl2(s)
9. The formal charges on Cl and O in the structure shown for the ClO- ion are, respectively:
(a)
(b)
(c)
(d)
(e)
0 and -1
-1 and 0
1 and -2
-2 and 1
None of the above
10. Select the correct Lewis structure for NOCl.
(a)
(b)
(c)
(d)
(e) None of these are correct.
3 of 9
CHEM 200/202 Fall 2016
Exam 3-A
November, 19 2016
11. How many electron pairs are shared between the carbon atoms in C2H4?
(a) 0
(b) 1
(c) 2
(d) 3
(e) 4
12. In which of the following molecules are all the bonds single?
(a)
(b)
(c)
(d)
(e)
O3
POCl3
CO
COCl2
N2H4
13. How many resonance structures are possible for NO3–?
(a)
(b)
(c)
(d)
(e)
1
2
3
4
5
14. In the following Lewis structure for phosphate, phosphorus has a formal charge of ____ and
an oxidation number of ____.
(a) 0, -3
(b) 0, 5
(c) 5, -3
(d) 5, 5
(e) 3, 5
15. In which one of the following species is the central atom (the first atom in the formula) likely
to violate the octet rule?
(a)
(b)
(c)
(d)
(e)
BF4
XeO3
SiCl4
NH3
CH2Cl2
4 of 9
CHEM 200/202 Fall 2016
Exam 3-A
November, 19 2016
16. What is the molecular structure of the thiocyanate anion, SCN–, as predicted by the VSEPR
theory? (Carbon is the central atom.)
(a)
(b)
(c)
(d)
(e)
linear
bent
trigonal planar
square planar
none of the above
17. What is the molecular structure around the carbons in CCl2CH2 as predicted by the VSEPR
theory?
(a)
(b)
(c)
(d)
(e)
linear
tetrahedral
trigonal planar
trigonal pyramidal
none of the above
18. What is the molecular structure of NH2Cl as predicted by the VSEPR theory?
(a)
(b)
(c)
(d)
(e)
trigonal planar
tetrahedral
T-shaped
trigonal pyramidal
see-saw
19. Which of the following bonds is the shortest?
(a)
(b)
(c)
(d)
(e)
C–N
C–O
C–C
C–Si
C–S
20. Of the figures below, which does not represent the formation of a sigma (σ) bond?
(e) None, they all
represent sigma bonds.
(a)
(b)
(c)
(d)
5 of 9
CHEM 200/202 Fall 2016
Exam 3-A
November, 19 2016
21. How many sigma (σ) and pi (π) bonds are there in a carbonate anion?
(a)
(b)
(c)
(d)
(e)
1 σ and 2 π
2 σ and 1 π
3 σ and no πac
3 σ and 1 π
3 σ and 2 π
22. Of the bonds listed below, which is the weakest?
(a)
(b)
(c)
(d)
(e)
A sigma (σ) bond
A pi (π) bond
A single bond
A double bond
A triple bond
Consider the structure of the molecule to the
right in answering the next three (3)
questions:
23. In the molecule depicted, how many
sigma (σ) and pi (π) bonds are present?
(a)
(b)
(c)
(d)
(e)
10 σ and 4 π
12 σ and 2 π
14 σ and 2 π
9 σ and 2 π
10 σ and 1 π
24. What is the hybridization of the oxygen atom on the molecule?
(a)
(b)
(c)
(d)
(e)
It is not hybridized
sp
sp2
sp3
sp3d
25. How many carbons on the molecule have trigonal planar molecular structure?
(a)
(b)
(c)
(d)
(e)
1
2
3
4
5
26. Below, each molecular geometry is paired with a possible hybridization. Which one is
incorrectly paired?
6 of 9
CHEM 200/202 Fall 2016
(a)
(b)
(c)
(d)
(e)
Exam 3-A
November, 19 2016
T-shaped - sp3
Linear - sp
Square planar - sp3d2
trigonal planar - sp2
bent - sp3
27. The hybridization diagram
(right) depicts the carbon
atom of one of the molecules
listed below. Identify the
correct molecule.
(a)
(b)
(c)
(d)
(e)
CO2
CH4
NCO
CH2O
CFCl3
For the following three (3) questions, use the molecular orbital diagrams below to aid in
obtaining your answers.
28. Using the appropriate molecular orbital diagram, for a molecule of BN– determine the
resulting bond order for the ion.
(a)
(b)
(c)
(d)
(e)
0.5
1
1.5
2
2.5
7 of 9
CHEM 200/202 Fall 2016
Exam 3-A
November, 19 2016
29. Which of the following diatomic molecules has the greatest number of electrons in
antibonding molecular orbitals?
(a)
(b)
(c)
(d)
(e)
CN–
O22–
F2+
BN+
N2
30. From the diatomic molecules below, identify ALL those that are diamagnetic. There is more
than one diamagnetic molecule, all diamagnetic molecules need to be identified in order to
get the correct answer.
(a)
(b)
(c)
(d)
(e)
O2
F2
C2
N 2–
B2
31. When considering a container which holds a gas, and the ideal gas law, which of these
statements is incorrect?
(a) When all other factors are held constant, the pressure is directly proportional to the
temperature of the gas.
(b) When all other factors are held constant, the volume is inversely proportional
to the number of moles of gas.
(c) When all other factors are held constant, the temperature is directly proportional to
the volume of the gas.
(d) When all other factors are held constant, pressure is inversely proportional to the
volume of the gas.
(e) When all other factors are held constant, the temperature is inversely proportional to
the number of moles of gas.
32. A balloon filled with 3.72 moles of nitrogen gas has a pressure of 1.42 atm at 23.5°C. The
balloon expands as the temperature of the gas inside the balloon increases to 47.0°C. If the
final pressure of the gas inside the balloon is 1.52 atm, what is the volume of the balloon?
(a)
(b)
(c)
(d)
(e)
63.8 L
0.500 L
128 L
64.3L
87.3 L
33. A 3.50 gram mass of a pure solid is placed into an empty, sealed, 675 mL container, and it is
heated until it becomes a gas. Once it has become a gas, at 249°C, the pressure inside the
container is 8.23 atm. What is the molecular mass of the solid?
(a) 27.0 g/mol
(b) 14.2 g/mol
(c) 0.0370 g/mol
8 of 9
CHEM 200/202 Fall 2016
Exam 3-A
November, 19 2016
(d) 32.4 g/mol
(e) 19.3 g/mol
34. What is the density (in g/L) of nitrogen gas (N2) when the gas has been pumped into a 50.0
L balloon at 23.8°C, and it has a pressure of 1.71 atm?
(a)
(b)
(c)
(d)
(e)
2.50 g/L
1.33 g/L
7.02 g/L
1.97 g/L
1.03 g/L
35. A 4.91 L cylinder has been filled with 25.0 grams of argon gas, 1.97 moles of neon gas, and
0.723 moles of xenon gas. What is the pressure inside the cylinder when it is at 32.1°C?
(a)
(b)
(c)
(d)
(e)
13.7 atm
21.9 atm
85.7 atm
18.3 atm
16.7 atm
36. A solid sample of calcium carbonate is dissolved with hydrochloric acid (see unbalanced
reaction below). The carbon dioxide produced from the reaction is all collected in a 2.50 L
cylinder, at 25.0°C. If the reaction is performed with 23.07 g of CaCO3 and 175 mL or 2.40
M HCl, what will be the pressure of the CO2 in the cylinder?
CaCO3(s) + HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)
(a)
(b)
(c)
(d)
(e)
4.62 atm
2.06 atm
2.25 atm
0.388 atm
1.00 atm
9 of 9