Chemistry 100 Final Exam (ALL SECTIONS)
April 22, 2010
M. Aquino; G. Orlova; B. MacLean/M. Leger
Name:_________________________________
ID: __________________________
This exam has a three-hour (3 hour) time limit.
Read over the entire exam before beginning. Do those questions that you find easiest in the
beginning. Proceed through the exam from the easier questions to the harder ones. Ration your
time according to the value of each question.
There should be twenty-eight different questions. A periodic table and an equation sheet are also
provided (attached to the back of your exam). If your exam does not contain 28 questions (16
total pages), notify the instructor immediately.
Answer all questions on this exam paper.
Read all questions carefully!! Please write legibly!!
Question
Full Marks Marks Earned Question Full Marks Marks Earned
Multiple Choice
32
22
8
17
4
23
8
18
4
24
8
19
4
25
8
20
4
26
8
21
4
27 or 28
8
Total
100
Have you put your name and ID at the top of this page?
2
PART (I). Multiple Choice. (32 marks, 2 marks each)
Please clearly circle the letter of your answer. If two or more answers are circled, the
question will be marked wrong regardless of whether the correct answer is circled. Wrong
answers will not be penalized, so guess if you have to!
1. A reaction that is not spontaneous at low temperature can become spontaneous at high
temperature if ΔH is ____ and ΔS is _____ .
a) +, +
b) 0, -
c) +, -
d) -, +
e) -, -
2. The molecular geometry of _______ is square pyramidal.
a) CH4
b) ClF5
c) PF5
d) NH3
e) BrCl3
3. From the molecules below, only _____ is non-polar.
a) PH3
b) H3COH
c) BH3
d) H3CCl
e) CO
4. ΔS is positive for the reaction:
a) 2H2 (g) + O2 (g)  2H2O (g)
b) 2NO2 (g)  N2O4 (g)
c) H2O (s)  H2O (l)
d) 2Hg (l) + O2 (g)  2HgO (s)
e) Ag+ (aq) + Cl- (aq)  AgCl (s)
5. The standard Gibbs free energy of formation of _____ is zero.
(I) NH3 (g)
a) (I) only
(II) N2 (g)
b) (II) only
(III) H (g)
c) (III) only
d) (I) and (II)
e) (I), (II), (III)
6. The n = 1 shell contains ____ p orbitals. All the other shells contain ____ p orbitals.
a) 3, 6
b) 0, 3
c) 6, 2
d) 3, 3
e) 0, 6
3
7. In general, as you go across a period in the periodic table from left to right:
(1) the atomic radius __________;
(2) the electron affinity becomes __________ negative; and
(3) the first ionization energy __________.
a) decreases, decreasingly, increases
b) increases, increasingly, decreases
c) increases, increasingly, increases
d) decreases, increasingly, increases
e) decreases, increasingly, decreases
8. Element M reacts with chlorine to form a compound with the formula MCl 2 . Element M is
more reactive than magnesium and has a smaller radius than barium. This element is _____.
a) Sr
b) K
c) Na
d) Ra
e) Be
9. Which of the following is NOT true about metals?
a) Metals tend to gain electrons
b) Metals tend to be good conductors of electricity
c) Metal oxides tend to be basic
d) Metals tend to be ductile
e) Metals are either solid or liquid at room temperature
10. Which of the following is a statement of the first law of thermodynamics?
a) Ek = ½ mv2
b) A negative H corresponds to an exothermic process
c) E = Efinal - Einitial
d) Energy lost by the system must be gained by the surroundings
e) 1 cal = 4.184 J (exactly)
4
11. For which of the following reactions is the value of Hrxn exactly equal to Hf for
the product?
a) 2 Ca (s)
b) C2H2 (g)
+
+
H2 (g)
c) 2 C (graphite)
d) 3 Mg (s)

O2 (g)
+
+
e) C (diamond)
+

C2H4 (g)

O2 (g)
N2 (g)
2 CaO (s)

O2 (g)
2 CO (g)
Mg3N2 (s)

CO2 (g)
12. If the rate law for the reaction: 2A + 3B  products is first order in A and second
order in B, then the rate law is: rate = ____________.
a) k[A][B]
b) k[A]2[B]3
c) k[A][B]2
d) k[A]2[B]
e) k[A]2[B]2
13. Of the following, ___________ will lower the activation energy for a reaction.
a) increasing the concentration of reactants
b) raising the temperature of the reaction
c) adding a catalyst for the reaction
d) removing products as the reaction proceeds
e) increasing the pressure
14. The general formula of an alkane is _________.
a) CnH2n + 2
b) C2nH2n + 2
c) CnH2n
d) CnH2n – 2
e) CnHn
15. Pentane has ___________ structural isomers.
a) 0
b) 1
c) 2
d) 3
e) 4
16. What is the general formula for an aldehyde?
a) R-O-R
b) R-CO-R’
c) R-CO-OH
d) R-OH
e) R-CHO
5
PART (II). Short Answer. (20 marks, each worth 4 marks). Please answer in the space
provided.
17. Using the table of average bond dissociation enthalpies below, calculate the ΔH rxn for the
reaction between acetylene (C2H2), and hydrogen (H2), to yield ethylene (C2H4):
C2H2 (g) + H2 (g)  C2H4 (g)
Bond
C≡C
C=C
C-C
H-H
C-H
18.
D (kJ/mol)
839
614
348
436
413
a) Give the full electron configuration of germanium (Ge).
b) Indicate which orbitals contain the valence electrons.
6
-
19. Explain briefly why the radius of a neon atom is smaller than the radius of an F ion, but
larger than the radius of a Na+ ion, despite the fact that all three particles have the same
electronic configuration.
20. Give the structure and name of the products for the following reactions (2 marks each):
a) Reaction of Br2 with benzene
b) Reaction of H2 with 1-butene
7
21. One way to remove H2S from industrial wastewaters is to treat the water with
chlorine, in which case the following reaction occurs:
H2S (aq)
+
Cl2 (aq)

S (s)
+
2 H+ (aq)
+ 2 Cl (aq)
The rate of this reaction is first order in each reactant. The rate constant for the
disappearance of H2S (at 28 C) is 3.5 x 102 M1s1. If, at a given time, the
concentration of H2S is 2.0 x 104 M and that of Cl2 is 0.025 M, what is the rate of
formation of Cl?
8
PART (III). Long Answer. (Answer 6 questions, each is worth 8 marks for a total of 48
marks). Please answer in the space provided.
22. Draw Lewis structures for NO+, N2O (connectivity is NNO), and NO3ˉ. Show resonance
structures if necessary and indicate the most plausible structures. For each atom, report
formal charges. Circle the structure, which has the longest N-O bond.
9
o
23. Calculate the equilibrium pressure of CO2 at 120 C using the following data:
PbCO3 (s)  PbO (s) + CO2 (g)
Substance
PbCO3 (s)
PbO (s)
CO2 (g)
ΔHof (kJ/mol)
-699.1
-217.3
-393.5
S (J/mol K)
131.0
68.70
213.6
at 25C
10
24. For the structure given below answer questions a), b), and c). Add electron lone pairs
on the appropriate atoms as needed. (Note that the subscripted numbers are labels
only)
H
H
C1
C2
H
O1
N
C3
H
C4
O2
H
a) There are ______ π-bonds and ______ σ-bonds in the structure
b) There are ______ lone pairs in the structure
c) What are the approximate bond angles in degrees for the following:
H –C1-C2
________
C1-C2-C3
________
C2-C3-C4
________
C3-C4-O2
________
C4-O2-H
________
11
25. The heat of combustion of ethanol, C2H5OH (l), is -1367 kJ/mol. A batch of
Sauvignon Blanc wine contains 10.6% ethanol by mass. Assuming the density of the
wine to be 1.0 g/mL, what caloric content (in Cal) does the ethanol in a 250 mL glass of the
wine have? (1 Cal = 1 kcal = 4.184 kJ)
12
26. The reaction: 2 ClO2 (aq) + 2 OH (aq)  ClO3 (aq) + ClO2 (aq) + H2O (l)
was studied with the following results:
Experiment
1
2
3
[ClO2] (M)
[OH] (M)
Rate (M/s)
0.060
0.020
0.020
0.030
0.030
0.090
0.0248
0.00276
0.00828
a) Determine the rate law for the reaction. (3 marks)
b) Calculate the rate constant. (Remember to include the correct units). (2 marks)
c) Calculate the rate when [ClO2] = 0.100 M and pH = 12.7. (3 marks)
13
NOTE: ANSWER QUESTION 27 OR QUESTION 28, NOT BOTH (IF YOU
ANSWER BOTH ONLY THE FIRST ONE WILL GET MARKED!)
27. Identify (circle and name) all four functional groups AND indicate (with an arrow) what the
hybridization is (eg. sp, sp2,sp3) at each carbon, for the molecule below.
H
O
C
C
H
O
N
C
C
H
O
H
N
H
H
H
O
H
14
28. Sort the following substances in increasing order of their boiling points (1 = lowest boiling
point, 4 = highest boiling point), and justify your answers by mentioning the predominant
intermolecular force and any other relevant characteristics of each molecule.
C4H9OH ___
NO ___
C6H14 ___
N2 ___
15
Equations
w  - Pop V  Pop V f  V i

q x  C x T  m x s x T f  T i

q x  C x T  C x T f  T i
q rxn  q sol 'n  q cal  0

E  E f  E i  q  w
r H    n p f H  products    n r f H  reactants 
r S    n p S  products    n r S  reactants 
univ S  sys S  surr S
surr S  
sys H

T surr
r G    n p f G  products    n r f G  reactants 
r H 
T surr
For the reaction aA  bB  cC  dD
rate = -
rate  k A  B 
X
 A
ln
 Ao

  kt

E  h 
0 h 2
me 2 Z
c  
 Z 2
 2
 n

 
pH  pK a  log

A 
HA 
pOH  - log OH 

1
k A o
d 2
 V  E 
8  2 m dx 2
h2
pK a  - logK a
pH  - log H 

t 12 =

E  1 1 
  - a 

R  T 2 T 1 

h

mv



kq 1 q 2
r
1 A 
1  [B]
1 [C]
1 [D]
==+
=+
a t
b t
c t
d t
1
1

 kt
A  A o
 n 2 where n  1 , 2 , 3...
 me 4
E n   2 2
 8 0 h
E ionic 
0.693
k
k
ln  2
 k1
ln k  ln A - E a /RT
rn 
y
t1 /2 
r G   RT ln K eq
r G   r H   Tr S 
Ax B y s   xAY  aq   yB X  aq 
  B 
K sp  AY 
x
X y
pH  pOH  14.00
K w = [ H 3 O + ][ OH - ]  [H  ][ OH - ]  1.0 x 10 14
m2
1 J  kg 2 ; 1 cal  4.184 J; 1 Cal  4.184 kJ  4184 J
s
16