KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS
CHEMISTRY DEPARTMENT
CHEM-102-132
FIRST MAJOR EXAM
March 5th, 2014
TEST CODE
STUDENT NUMBER:
NAME :
SECTION NUMBER:
000
_____________________________
_____________________________
_____________________________
INSTRUCTIONS
1.
2.
3.
4.
5.
6.
Write your student number, name, and section number on the EXAM COVER page.
Write your student number, section number, and your name on your EXAM ANSWER
FORM.
Bubble in pencil your student number and your section number on the EXAM ANSWER
FORM.
Bubble in pencil on your EXAM ANSWER FORM the correct answer to each of the
questions. .
You must not give more than ONE answer per question.
At the end of the exam return the EXAM ANSWER FORM to the proctor.
The exam contains 20 multiple choice questions and the time allowed is 80 min.
PLEASE TURN OFF YOUR CELL PHONE AND
PLACE IT UNDER YOUR SEAT
Important constants
Gas Constant (R)
Planck’s Constant (h)
Speed of light (c)
Avogadro’s number (N)
Bohr’s Constant (RH)
Faraday (F)
Specific heat of H2O
= 0.08206
= 8.314
= 8.31 x 107
= 6.626 x 10-34
= 6.626 x 10-34
= 2.998 x 108
= 6.022 x 1023
= 2.179 x 10-18
= 96485
= 4.18
Page 1
L.atm/(mol.K)
J/(mol.K)
g.cm2/(sec2.mol.K)
J.sec/particle
kg.m2/(sec.particle)
m/sec
particles/mole
J/particle
Coulombs/mol eJ/(g.oC)
Name: __________________________ Date: _____________
1. The gas-phase reaction between methane and diatomic sulfur is given by the
equation:
CH4(g) + 2S2(g)
CS2(g) + 2H2S(g)
At 550 oC the rate constant is 1.1 M-1.s-1 and at 625 oC the rate constant is
6.4 M-1.s-1. The activation energy for this reaction is:
A)
B)
C)
D)
144 kJ/mol
477 kJ/mol
67 kJ/mol
222 kJ/mol
2. For the hypothetical reaction
could be expressed as:
A)
B)
C)
D)
A + 3B → 2C, the rate of appearance of C given
‒(⅔) Δ[B]/Δt
‒(½) Δ[A]/Δt
‒Δ[A]/Δt
‒(3/2) Δ[B]/Δt
3. The reaction
A→B+C
has a rate constant of 5.0×10-2 M.s-1 at 25oC. An
o
experiment was run at 25 C where the initial concentration of A was 1.0×10-3 M.
Calculate the concentration of B after 5.0×10-3 s has passed.
A)
B)
C)
D)
2.510-4 M
7.510-4 M
1.2510-3 M
3.510-3 M
Page 2
4. The mechanism shown below is proposed for the reaction:
2N2O5(g) → 4NO2(g) + O2(g).
What rate law does the mechanism predict?
k1
N2O5
NO2 + NO3
Fast
k-1
k2
NO2 + NO3
NO2 + O2 + NO Slow
NO + N2O5
A)
B)
C)
D)
k3
3 NO2
Fast
Rate = k[N2O5]
Rate = k
Rate = k[N2O5]2
Rate = k[N2O5][NO3]
5. The graphs below both refer to the same reaction. What is the order of this reaction?
A)
B)
C)
D)
Zeroth order
First order
Second order
cannot be determined from the information given
6. A certain reaction described by the equation
has a Kc value of
A)
B)
C)
D)
A(g) + 2B(g)
3C(g)
x. What is the value of KP at the same reaction conditions?
x
x(RT )
x
RT
3
x
2
Page 3
7. The reaction quotient for a system is 7.2×102. If the equilibrium constant for the same
system is 36, what will happen as equilibrium is approached?
A)
B)
C)
D)
There will be more reactants produced.
There will be more products produced.
The reaction quotient will stay unchanged.
There will be both more products and more reactants produced.
8. Consider the two gaseous equilibria:
SO2(g) + ½O2(g)
SO3(g)
2SO3(g)
2SO2(g) + O2(g)
K1
K2
The values of the equilibrium constants K1 and K2 are related by:
A)
B)
C)
D)
2
K2 = 1/K1
2
K1 = 1/K2
K1 = ‒2K2
K2 = ‒2K1
9. 1.25 moles of NOCl were placed in a 2.50 L reaction flask at 427ºC.
After equilibrium was reached, 1.10 moles of NOCl remained.
Calculate the equilibrium constant, Kc, for the reaction:
2NOCl(g)
A)
B)
C)
D)
2NO(g) + Cl2(g)
5.6 10-4
1.8 103
1.4 10-3
7.1 102
10. Find the [OH‒] in a 0.250 M aqueous solution of ethylamine (C2H5NH2).
For ethylamine, Kb = 5.6 10-4.
A)
B)
C)
D)
0.012 M
11.52 M
0.238 M
0.033 M
Page 4
11. Classify the aqueous solution of each of the following species (in the given order) as
expected to be basic, acidic or neutral (i.e., neither acidic nor basic):
CN , ClO3 , C2H3O2 ,
(CH3)2NH
A)
B)
C)
D)
basic, neutral, basic, basic
basic, basic, basic, basic
basic, neutral, basic, acidic
neutral, neutral, basic, acidic
12. What mass of HI should be present in 0.250 L of solution to obtain a solution with
pH = 1.25?
A)
B)
C)
D)
1.8 g
7.2 g
12.4 g
3.1 g
13. Which of the following titrations curves would represent a 0.10 M NaOH
solution being titrated with a 0.10 M HNO3 solution?
A)
B)
C)
D)
Page 5
14. Which of the following acids is the strongest?
A)
B)
C)
D)
HClO2(aq)
HBrO2(aq)
HIO2(aq)
HIO(aq)
15. Calculate the concentration of HCO3- in a 0.025 M H2CO3 solution?
For H2CO3, Ka1 = 4.210-7 and Ka2 = 4.810-11.
A)
B)
C)
D)
1.0  10-4 M
4.8  10-11 M
2.1  10-7 M
5.3  10-9 M
16. What would be the pH value when 1.0 g of solid NaOH is added to a 1.0 L of
0.10 M formic acid (HCO2H) / 0.20 M sodium formate (HCO2Na) solution?
Ka of formic acid is 1.710-4 .
A)
B)
C)
D)
4.25
4.04
3.44
3.26
17. 50.00 mL of 0.10 M HNO2 (nitrous acid, Ka = 4.5 × 10-4) is being titrated with a 0.10
M KOH solution. After 25.00 mL of the KOH solution is added, the pH in the
titration flask will be
A)
B)
C)
D)
3.35
2.17
1.48
7.00
18. Will a precipitate of PbCl2 form when 0.10 L of 3.0 × 10-2 M Pb(NO3)2 is added to
400 mL of 9.0 × 10-2 M NaCl? For PbCl2, Ksp = 2.4 × 10-4.
A)
B)
C)
D)
No, because Q < Ksp
Yes, because Q > Ksp
Yes, because Q < Ksp
No, because Q = Ksp
Page 6
19. At 500.0 K, gaseous NOBr is placed in a container, and is found at equilibrium to be
9.0% dissociated according to the equation:
2NOBr(g)
2NO(g) + Br2(g)
If the total pressure at equilibrium is 0.17 atm, the equilibrium constant (Kc) for this
reaction is:
A)
B)
C)
D)
1.7510-6
7.2110-5
2.9610-3
3.4010-2
20. Which compound is more soluble in an acidic solution than in a neutral solution?
A)
B)
C)
D)
BaF2
PbBr2
AgI
CuCl
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Answer Key
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A
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