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Chemistry 112 Name _______________________
Exam I Form A Section _______________________
September 16, 2014 eMail _______________________
IMPORTANT: On the scantron (answer sheet), you MUST clearly fill your name, your student number, section number, and test form (white cover = test form A; yellow cover = test form B). Use a #2 pencil.
There are 25 questions on this exam. Check that you have done all of the problems and filled in the first 25 bubbles on the scantron. The maximum score on this exam is 25 points. Your score will be reported in percent (max 100%).
Exam policy
• Calculators with text-programmable memory are not allowed. • Relevant data and formulas, including the periodic table, are attached at the end of this
exam. • Your grade will be based only on what is on the scantron form. • The answer key will be posted on the web after the exam (on the Exam Schedule page). • You must turn in your cover sheet with your scantron answer form.
Hints
• As you read the question, underline or circle key words to highlight them for yourself. Avoid errors from "mis-reading" the question.
• Pay attention to units and magnitudes (decimal places) of numbers obtained from calculations.
• There is no penalty for guessing.
CHEMISTRY 112 EXAM 1 Form A
Sept. 16, 2014
1. Which of the following correctly describes the above reaction? A) Exothermic with 2 activated complexes and 3 intermediates B) Endothermic with 2 activated complexes and 3 transition states C) Endothermic with 3 transition states and 2 intermediates D) Endothermic with 2 reactants and 3 products E) Exothermic with 2 activated complexes and 3 intermediates 2. What is the missing product in this fission reaction?
235U + 1n → 3 1n + 90Sr + ___ A) 142I B) 143I C) 146I D) 142Xe E) 143Xe 3. Which of the following is true? A) Beta decay results in the conversion of a proton into a neutron. B) Positron emission increases the nuclear charge of an atom. C) Nuclear decay always follows second-order kinetics. D) Gamma decay produces high-energy radiation. E) Alpha decay decreases the atomic number of the parent atom by 1. ---------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------PLEASE USE THE FOLLOWING KINETIC DATA TO ANSWER THE FOLLOWING 2 QUESTIONS ABOUT THIS REACTION: A + B + C → P + R
Experiment [A] (M) [B] (M) [C] (M) Reaction Rate (M/s)
1 0.40 0.40 0.40 2.0 x 10−4 2 0.80 0.40 0.40 4.0 x 10−4 3 0.40 0.80 0.40 2.0 x 10−4 4 0.40 0.80 0.80 8.0 x 10−4
-------------------------------------------------------------
4. What is the rate law for this reaction? A) Rate = k[A][B][C]2
B) Rate = k[A]2[B][C]2
C) Rate = k[A][C]2 D) Rate = k[A]1/2[B][C]2 E) Rate = k[A]2[C]3
------------------------------------------------------------- 5. What is the value of the rate constant, k and its units? A) 3.13 x 10−3 M−2s−1 B) 1.25 x 10−3 M−2s−1 C) 2.00 x 10−4 M−1s−1 D) 3.13 x 10−3 M−1s−1 E) 6.40 x 10−2 M−1s−1 6. Acetaminophen is eliminated from cerebrospinal fluid of the body with a first order half-life of 3.2 hours. If the concentration of acetaminophen in an ailing student is 15 µL/mL at 1:00 pm, what will be the concentration at 8:00 pm? A) 3.29 µL/mL B) 13.00 µL/mL C) 4.37 µL/mL D) 0.22 µL/mL E) The drug will be completely cleared from the cerebrospinal fluid. ---------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------- 7. Which of the following isotopes is most likely to undergo fusion? A) Helium-4 B) Iron-56 C) Uranium-235 D) Uranium-238 E) Mendelevium-256 8. Ethanol decomposes on an alumina surface with a second-order rate constant of 4.00 x 10-5 M−1s−1 at 600 K. If the initial concentration of ethanol is 0.5 M, what is the concentration after 8 hours? A) 0.13 M B) 0.17 M C) 0.23 M D) 0.27 M E) 0.32 M 9. The decomposition of Compound A was studied and the following data were collected. The slope of the line is −0.073 s−1 and the y-intercept is 0.40. What is the half-life of Compound A? A) 0.07 s B) 0.40 s C) 9.50 s D) 13.70 s E) 34.20 s 10. Which of the following isotopes are most likely to undergo beta decay? A) 1H B) 12N C) 14C D) 19Ne E) 235U
--------------------------------------------------------------------------------------------------------------------- PLEASE USE THE FOLLOWING 3-STEP MECHANISM TO ANSWER THE FOLLOWING 2 QUESTIONS:
NO (g) + NO (g) → N2O2 (g) (fast) N2O2 (g) + H2 (g) → N2O (g) + H2O (g) (slow)
N2O (g) + H2 (g) → N2 (g) + H2O (g) (fast)
------------------------------------------------------------- 11. What is the rate law for the overall reaction? A) Rate = kobs[NO]2 B) Rate = kobs[N2O2][H2] C) Rate = kobs[N2O][H2] D) Rate = kobs[NO]2[H2] E) Rate = kobs[NO][N2O2][H2]
------------------------------------------------------------- 12. What is the role of N2O in this reaction mechanism? A) reactant B) product C) catalyst D) activated complex E) intermediate 13. Which of the following statements are true about catalysts?
i. A catalyst increases the value of the equilibrium constant, Keq. ii. A catalyst lowers the activation energy of the reaction, Ea. iii. A catalyst lowers the energy of the products and stabilizes them.
A) i only B) ii only C) iii only D) ii and iii only E) All of the above 14. What is the final product when Uranium-238 undergoes 5 alpha decay reactions and 2 beta decay reactions? A) radon-226 B) lead-218 C) polonium-218 D) plutonium-244 E) radium-226
--------------------------------------------------------------------------------------------------------------------- 15. Chlorofluorocarbons are known to have a damaging effect on the ozone layer because chlorotrifluoromethane (CF3Cl), once commonly used as a refrigerant, can split into the free radicals CF3 and Cl in the atmosphere. The radical Cl then reacts as follows:
Cl + O3 → ClO + O2 ClO + O → Cl + O2
What is the concern with the free radical Cl with respect to the ozone layer? A) It acts as a reactant, consuming ozone (O3). B) It acts as a catalyst, consuming ozone (O3). C) It creates a very high-energy transition state. D) It creates ClO, a potent catalyst. E) It is a product in the overall reaction, creating a poisonous free radical in the lower stratosphere. 16. Glucose (C6H12O6) is combusted according to the following equation:
C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (g)
When glucose is being consumed at a rate of 0.12 moles per second, what is the rate of production of carbon dioxide? A) 0.02 mol/s B) 0.12 mol/s C) 0.24 mol/s D) 0.60 mol/s E) 0.72 mol/s 17. A present-day rock is found to contain 2.70 g of 238U and 1.72 g of 206Pb. What is the age of the rock? (The half-life of the decay of 238U to 206Pb is 4.51 x 109 years.) A) 3.21 x 109 y B) 3.59 x 109 y C) 4.11 x 109 y D) 4.56 x 109 y E) 4.99 x 109 y
--------------------------------------------------------------------------------------------------------------------- 18. A 100 mL flask is filled with 0.124 moles of A and allowed to react to form product B according to the following reaction:
2 A(g) → B(g) The data in the table are obtained for [A]t as the reaction proceeds. How many moles of B are present at 40 seconds? Time (s) 0.0 10.0 20.0 30.0 40.0 Moles of A 0.124 0.110 0.088 0.073 0.054 A) 0.070 moles B) 0.035 moles C) 0.140 moles D) 0.054 moles E) 0.027 moles 19. A group of ambitious Penn State graduate students synthesize a new element and decide to call it Nittnium. Further experimentation determines the half-life of Nittnium to be 1,855 s. The students create a batch of Nittnium to run experiments on, but then they let it sit for one hour while they run to West Halls to grab some cookies. What fraction of Nittnium will remain when they get back to their lab? A) 3% B) 14% C) 26% D) 34% E) 48% 20. Graduate students at a different university synthesize their own new element and decide to call it Pittonium. Immediately upon synthesis of the sample, the students observe an activity of 160 disintegrations per second. After 16 minutes, the students observe an activity of only 10 disintegrations per second. What is the half-life of Pittonium? A) 1.6 minutes B) 4.0 minutes C) 3.2 minutes D) 8.0 minutes E) 4.8 minutes
21. What is the nuclear binding energy of 1 mole of Lithium-7 nuclei? (The atomic mass of one Lithium-7 nucleus is 7.016003 amu.) A) 7.023 x 103 KJ B) 9.126 x 105 KJ C) 5.226 x 106 KJ D) 3.644 x 109 KJ E) 7.424 x 1017 KJ 22. The progress of the reaction A → B is shown below where the dark spheres represent A molecules and the light spheres represent B molecules. What is the rate constant in this reaction? t = 0 s t = 20 s t = 40 s A) 0.075 s−1 B) 0.120 s−1 C) 1.330 s−1 D) 0.017 s−1 E) 0.035 s−1 23. If a reaction is twice as fast at 123°C than it is at 23°C, then what is its activation energy? A) 100 J/mol B) 163 J/mol C) 6.9 KJ/mol D) 24.2 KJ/mol E) 100 KJ/mol ---------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------- 24. Which of the following statements are true regarding endothermic reactions?
i. The reverse reaction will have a lower Ea than the forward reaction. ii. An endothermic reaction requires a catalyst to proceed in the forward direction. iii. An endothermic reaction releases energy.
A) i only B) ii only C) iii only D) i and ii only E) All of the above are true 25. Substances A and B react with each other such that A is 75% consumed in 16 minutes and A is 87.5% consumed in 24 minutes. Changing the concentration of B has no effect on the reaction rate. The reaction is: A) Zero order in both A and B B) First order in both A and B C) Second order in A and zero order in B D) First order in A and zero order in B E) There is insufficient information to answer this question --------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------
END OF EXAM
Chem 112 Equations Constants, Conversions And Equations For Use During Exams And Quizzes
Conversions Constants
1J kg m2 s2 C V c 2.99792458 108 m s1 R 0.08206 L atm mol1 K1
1A C s1 h 6.63 1034 J s R 8.314 J mol1 K1
1g 6.021023 amu F 96,485 C mol1 01 n 1.0086649 amu
NA 6.0221023 mol1 1
1 p 1.0072765 amu
KW 11014 at 25 oC
Equations
k Ae
Ea
RT
Rate kN G H TS nFE
ln k E
a
RT ln A ln
Nt
N0
0.693t
t1 2
kt Go 2.303 RT log K RT ln K
ln A ln A 0 kt E= h hc
G Go RT ln Q
lnk
1
k2
E
a
R
1T
2
1T
1
E = mc2 G Go 2.303 RT log Q
t1 2
ln2k
0.693
k K
aK
b K
W H OH Eo
0.0592n
log K at 25 oC
1A
1
A 0
kt pH pKa log
X HX
E Eo 0.0592
nlog Q at 25 oC
Kp
= Kc
RT n pKW pHpOH pK
a pK
b
Molecular Orbital Theory Diagrams Crystal Field Theory Diagram Color Wheel with Wavelength Ranges
Chem 112 Equations Constants, Conversions And Equations For Use During Exams And Quizzes
Standard Reduction Potentials in Water at 25°C Half Reaction E°1/2(V)
PERIODIC TABLE of the ELEMENTS MAIN GROUPS MAIN GROUPS
1A 1
8A 18
1 H
1.008
2A 2
3A 13
4A 14
5A 15
6A 16
7A 17
2 He
4.003
3 Li
6.941
4 Be
9.012
TRANSITION METALS
5 B
10.811
6 C
12.011
7 N
14.007
8 O
15.999
9 F
18.998
10 Ne
20.180
11 Na
22.990
12 Mg
24.305
3B 3
4B 4
5B 5
6B 6
7B 7
8B 8
8B 9
8B 10
1B 11
2B 12
13 Al
26.982
14 Si
28.086
15 P
30.974
16 S
32.066
17 Cl
35.453
18 Ar
39.948
19 K
39.098
20 Ca
40.078
21 Sc
44.956
22 Ti
47.867
23 V
50.942
24 Cr
51.996
25 Mn
54.938
26 Fe
55.845
27 Co
58.933
28 Ni
58.693
29 Cu
63.546
30 Zn
65.39
31 Ga
69.723
32 Ge 72.61
33 As
74.992
34 Se
78.96
35 Br
79.904
36 Kr
83.80
37 Rb
85.468
38 Sr
87.62
39 Y
88.906
40 Zr
91.224
41 Nb
92.906
42 Mo 95.94
43 Tc [98]
44 Ru
101.07
45 Rh
102.90
46 Pd
106.42
47 Ag
107.87
48 Cd
112.41
49 In
114.82
50 Sn
118.71
51 Sb
121.76
52 Te
127.60
53 I
126.90
54 Xe
131.29
55 Cs
132.91
56 Ba
137.33
57 La*
138.91
72 Hf
178.49
73 Ta
180.95
74 W
183.84
75 Re
186.21
76 Os
190.23
77 Ir
192.22
78 Pt
195.08
79 Au
196.97
80 Hg
200.59
81 Tl
204.38
82 Pb
207.2
83 Bi
208.98
84 Po [209]
85 At
[210]
86 Rn [222]
87 Fr
[223]
88 Ra [226]
89 Ac** [227]
104 Rf
[261]
105 Db [262]
106 Sg [266]
107 Bh [264]
108 Hs [265]
109 Mt [268]
110
[269]
111
[272]
112
[277]
114
[285]
116
[289]
118
[293]
* LANTHANOIDS 58 Ce
140.12
59 Pr
140.91
60 Nd
144.24
61 Pm [145]
62 Sm
150.36
63 Eu
151.96
64 Gd
157.25
65 Tb
158.92
66 Dy
162.50
67 Ho
164.93
68 Er
167.26
69 Tm
168.93
70 Yb
173.04
71 Lu
174.97
** ACTINOIDS
90 Th
232.04
91 Pa
231.04
92 U
238.03
93 Np [237]
94 Pu [244]
95 Am [243]
96 Cm [247]
97 Bk [247]
98 Cf
[251]
99 Es [252]
100 Fm [257]
101 Md [258]
102 No [259]
103 Lr
[262]
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