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Pretest 1
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1.
a.
b.
c.
d.
e.
Which one of the following thermodynamic quantities is not a state function?
work
enthalpy
entropy
internal energy
free energy
____
2.
The enthalpy change, H, of a process is defined as:
a. The maximum amount of useful work that can be done in a system.
b. The increase or decrease in temperature in a system.
c. The quantity of heat transferred in or out of a system as it undergoes a change at constant
pressure.
d. The change in molecular disorder in a system.
e. None of these are correct.
____
3.
A system is compressed from 50.0 L to 5.0 L at a constant pressure of 10.0 atm. What is the amount
of work done?
a. 2.5  105 J
b. 450 J
c. 4.6  104 J
d. 450 J
e. 4.6  104 J
____
4.
If 4.168 kJ of heat is added to a calorimeter containing 75.40 g of water, the temperature of the water
and the calorimeter increases from 24.58C to 35.82C. Calculate the heat capacity of the calorimeter (in
J/C). The specific heat of water is 4.184 J/gC.
a. 622 J/C
b. 55.34 J/C
c. 315.5 J/C
d. 25.31 J/C
e. 17.36 J/C
____
5.
A 50.0 mL solution of 1.2 M HCl at 24.1C is mixed with 50.0 mL of 1.3 M NaOH, also at 24.1C, in
a coffee-cup calorimeter. After the reaction occurs, the temperature of the resulting mixture is 29.8C. The
density of the final solution is 1.05 g/mL. Calculate the molar heat of neutralization. Assume the specific heat
of the solution is 4.184 J/gC. The heat capacity of the calorimeter is 32.5 J/C.
a. 41.7 kJ/mol
b. 58.5 kJ/mol
c. 44.8 kJ/mol
d. 13.0 kJ/mol
e. 33.9 kJ/mol
____
6.
The burning of 80.3 g of SiH4 at constant pressure gives off 3790 kJ of heat. Calculate H for this
reaction.
SiH4(g) + 2O2(g)  SiO2(s) + 2H2O
a.
b.
c.
d.
e.
____
1520 kJ/mol rxn
47.2 kJ/mol rxn
4340 kJ/mol rxn
2430 kJ/mol rxn
+4340 kJ/mol rxn
7.
Given the following at 25C and 1.00 atm:
1/2N2(g) + O2(g)  NO2(g)
N2(g) + 2O2(g)  N2O4(g)
H0 = 33.2 kJ
H0 = 11.1 kJ
Calculate the H0 for the reaction below at 25C.
2NO2(g)  N2O4(g)
a.
b.
c.
d.
e.
____
8.
Given the standard heats of formation for the following compounds, calculate
reaction.
CH4(g)
+ H2O(g)
+ H2(g)

CH3OH
0
75
242
238
(kJ/mol)
a.
b.
c.
d.
e.
____
+11.0 kJ
+44.3 kJ
+55.3 kJ
22.1 kJ
55.3 kJ
+79 kJ
79 kJ
+594 kcal
594 kcal
405 kJ
9.
Estimate the heat of reaction at 298 K for the reaction shown, given the average bond energies below.
Br2(g) + 3F2(g)  2BrF3(g)
Bond
BrBr
FF
BrF
a.
b.
c.
d.
e.
____
10.
for the following
Bond Energy
193 kJ/mol
155 kJ/mol
249 kJ/mol
836 kJ
150 kJ
89 kJ
665 kJ
1222 kJ
Which of the following is not a formation reaction?
a. 1/2H2(g) + 1/2Br2
 HBr(g)
b. H2(g) + 1/2O2(g)  H2O
c. Ca(s) + 1/2O2(g)  CaO(s)
d. 4Al(s) + 3/2O2(g)  Al2O3(s)
e. H2O
+ SO3
 H2SO4
____
11.
Which one of the following statements is false? For a reaction carried out at constant temperature and
constant pressure in an open container, ____.
a. the work done by the system can be set equal to PV
b. the work done by the system can be set equal to VP
c. the work done by the system can be set equal to nRT where n is the number of moles
of gaseous products minus the number of moles of gaseous reactants
d. the heat absorbed by the system can be called qp
e. the heat absorbed by the system can be called H
____
12.
The heat of vaporization of methanol, CH3OH, is 35.20 kJ/mol. Its boiling point is 64.6C. What is
the change in entropy for the vaporization of methanol?
a. 17.0 J/molK
b. 3.25 J/molK
c. 17.0 J/molK
d. 104 J/molK
e. 543 J/molK
____
13.
Use the data below to calculate
2C6H6
+ 15O2(g)  12CO2(g) + 6H2O
= 393.5 kJ/mol,
____
, at 25C and 1 atm.
H0 = 6535 kJ
= 285.8 kJ/mol
a.
b.
c.
d.
e.
49.1 kJ/mol
3.51  104 kJ/mol
103 kJ/mol
1.76  103 kJ/mol
561 kJ/mol
14.
Calculate the standard energy change, E0, for the reaction below.
12NH3(g)
+ 21O2(g)
+ 4NO(g)

8HNO3
0
91.3
45.9
133.9
(kJ/mol)
a.
b.
c.
d.
e.
____
for benzene, C6H6
15.
+ 14H2O(g)
241.8
3,540 kJ/mol
201.3 kJ/mol
2,259 kJ/mol
4270 kJ/mol
3,503 kJ/mol
What is the entropy change of the reaction below at 298 K and 1 atm pressure?
N2(g)
+ 3H2(g)
2NH3(g)

191.5
(J/molK)
____
130.6
192.3
a.
b.
c.
d.
e.
198.7 J/K
76.32 J/K
129.7 J/K
303.2 J/K
384.7 J/K
16.
a.
b.
c.
d.
Which chemical change listed below represents a decrease in entropy?
N2(g) + 3H2(g)  NH3(g)
CaCO3(s)  CaO(s) + CO2(g)
2NO2(g)  N2(g) + 2O2(g)
2C6H6
e. 2NaCl
+ 15O2(g)  12CO2(g) + 6H2O(g)
 2Na
+ Cl2(g)
____
17.
a.
b.
c.
d.
e.
Which of the following statements regarding the third law of thermodynamics is incorrect?
The absolute S is zero at 0 Kelvin.
The absolute S at 298 K can be positive or negative.
Pure substances have positive absolute S at T > 0 Kelvin.
Absolute zero gives a reference point for determining absolute S.
The absolute S is greater at 300 K than 100 K for a given substance.
____
18.
a.
b.
c.
d.
e.
A process occurs spontaneously and Ssystem < 0. Which statement below must be true?
Ssurroundings > 0
Suniverse > 0
The pressure is constant.
Both (a) and (b) are correct.
All of these answers are correct.
____
19.
For a particular reaction at 25C, H0 = 297 kJ/mol, and S0 = 113.3 J/molK. At which of the
following temperatures would the reaction become spontaneous?
a. 2750 K
b. 3250 K
c. 2450 K
d. 10500 K
e. 3750 K
____
20.
Calculate G0 for the reaction below. The standard molar entropy change for the reaction at 298 K is
287.5 J/molK.
3NO2(g) + H2O
a.
b.
c.
d.
e.
____
21.
 2HNO3(aq) + NO(g) + 136.8 kJ
51.2 kJ/mol
85,500 kJ/mol
68.4 kJ/mol
236 kJ/mol
222 kJ/mol
Evaluate G0 for the reaction below at 25C.
(kJ/mol)
a.
b.
c.
d.
e.
2C2H2(g)
209.2
+ 5O2(g)
0

4CO2(g)
394.4
+ 2H2O
237.2
1409 kJ
2599 kJ
1643 kJ
2470 kJ
766 kJ
____
22.
For which set of values of H and S will a reaction be spontaneous (product-favored) at all
temperatures?
a. H = +10 kJ, S = 5 J/K
b. H = 10 kJ, S = 5 J/K
c. H = 10 kJ, S = +5 J/K
d. H = +10 kJ, S = +5 J/K
e. no such values exist
____
23.
In the following reaction, the rate of formation of NH3 is 0.15 mol/Lmin. What is the rate of
reaction?
N2 + 3H2  2NH3
a.
b.
c.
d.
e.
____
24.
Suppose a reaction A + B  C occurs at some initial rate at 25C. Which response includes all of the
changes below that could increase the rate of this reaction?
I.
lowering the temperature
II.
adding a catalyst
III.
increasing the initial concentration of B
a.
b.
c.
d.
e.
____
0.15 mol/Lmin
0.075 mol/Lmin
0.075 mol/Lmin
0.20 mol/Lmin
0.30 mol/Lmin
I
II
III
I and II
II and III
25.
The gas phase reaction A + B + C  D has a reaction rate which is experimentally observed to follow
the relationship rate = k[A]2[C]. The reaction is ____ order in A, ____ order in B, and ____ order in C.
a. first; second; third
b. first; second; zero
c. second; zero; first
d. second; first; zero
e. second; zero; zero
____
26.
A hypothetical reaction X + 2Y  Products is found to be first order in X and second order in Y.
What are the units of k, the specific rate constant, if reaction rate is expressed in units of moles per liter per
second?
a. Ms1
b. M2s1
c. M3s
d. M2s1
e. M1s
____
27.
A troublesome reaction that is responsible in part for acid rain is
SO3 + H2O  H2SO4
Rate data have been determined at a particular temperature for the reaction in which all reactants and products
are gases.
Trial Run
1
2
3
4
Initial [SO3]
0.35 M
0.70 M
0.35 M
0.70 M
Initial [H2O]
0.35 M
0.35 M
0.70 M
0.70 M
Initial Rate (Ms1)
0.150
0.600
0.300
1.20
The rate-law expression is ____.
a. rate = k[SO3]2[H2O]2
b. rate = k[SO3]2[H2O]
c. rate = k[SO3][H2O]2
d. rate = k[SO3]2
e. rate = k[SO3][H2O]
28.
a.
b.
c.
d.
e.
____
29.
The rate constant for the first order reaction below is k = 3.3  102 min1 at 57 K. What is the half-life
for this reaction at 57 K?
A  B + C
a.
b.
c.
d.
e.
____
A plot of
second
first
zero
one-half
negative one
versus time is linear for the reaction D  E. What is the kinetic order of the reaction?
____
21 min
30 min
61 min
9.1 min
1200 min
30.
A molecule of ethyl alcohol is converted to acetaldehyde in one's body by zero order kinetics. If the
concentration of alcohol is 0.015 mol/L and the rate constant = 6.4  105 mol/Lmin, what is the
concentration of alcohol after 3.5 hours?
a. 0.0016 mol/L
b.
c.
d.
e.
____
9.6  107 mol/L
4.3  103 mol/L
0.15 mol/L
0.0032 mol/L
31.
The specific rate constant, k, for a reaction is 2.64  102 s1 at 25C, and the activation energy is 74.0
kJ/mol. Calculate k at 50C. (The universal gas constant = 8.314 J/molK.)
a.
b.
c.
d.
e.
0.832 s1
71.9 s1
0.266 s1
1.08 s1
0.0265 s1
____
32.
a.
b.
c.
d.
e.
Which of the following statements about catalysts are false?
A catalyst lowers the activation energy.
A catalyst can make a nonspontaneous reaction spontaneous.
A catalyst speeds up both the forward and reverse reaction.
A catalyst speeds up the rate of reaction.
Catalyst are often transition metals and transition metal oxides.
____
33.
Consider the hypothetical reaction shown below.
A + 2B  AB2
Assume that the following proposed mechanism is consistent with the rate data.
B
B2
B
A
+
+
+
+
B  B2
A  AB + B
AB  AB2
2B  AB2
slow
fast
fast
overall
Which one of the following statements must be true? The reaction is ____.
a. first order in A, second order in B, and third order overall
b. second order in B and second order overall
c. first order in A and first order overall
d. second order in B, zero order in A, and third order overall
e. second order in A and second order overall
____
34.
Which idea listed below is not a part of the collision theory of reaction rates?
a. Molecules must be properly oriented when they collide to react.
b. Molecules must collide to react.
c. Molecules must collide with enough kinetic energy to overcome the potential energy
stabilization of the bonds.
d. Effective collisions result in a chemical reaction.
e. All molecular collisions result in a reaction.
____
35.
Which statement is incorrect?
a. Energy is the capacity to do work or to transfer heat.
b. Kinetic energy is the energy of motion.
c. Potential energy is the energy that a system possesses by virtue of its position or
composition.
d. A process that absorbs energy from its surroundings is called exothermic.
e. The Law of Conservation of Energy is another statement of the First Law of
Thermodynamics.
____
36.
How much heat is absorbed in the complete reaction of 3.00 grams of SiO 2 with excess carbon in the
reaction below? H0 for the reaction is +624.6 kJ.
SiO2(g) + 3C(s)  SiC(s) + 2CO(g)
a.
b.
c.
d.
e.
366 kJ
1.13  105 kJ
5.06 kJ
1.33  104 kJ
31.2 kJ
____
37.
a.
b.
c.
d.
e.
Which statement concerning sign conventions for E = q + w is false?
For heat absorbed by the system, q is positive.
For work done by the system, w is negative.
When energy is released by the reacting system, E is negative.
If E is positive, energy can be written as a product in the equation for the reaction.
For an expansion, w is negative.
____
38.
A 1.00-g sample of hexane, C6H14, undergoes complete combustion with excess O2 in a bomb
calorimeter. The temperature of the 1500. g of water surrounding the bomb rises from 22.64C to 29.30C.
The heat capacity of the calorimeter is 4.04 kJ/C. What is E for the reaction in kJ/mol of C6H14. The
specific heat of water is 4.184 J/gC.
a. 9.96  103 kJ/mol
b. 4.52  103 kJ/mol
c. 1.15  104 kJ/mol
d. 7.40  104 kJ/mol
e. 5.91  103 kJ/mol
____
39.
a.
b.
c.
d.
e.
____
40.
A positive change in entropy represents:
an increase in dispersal of matter (molecular disorder)
release of thermal energy
a decrease in thermal energy
a process that is always spontaneous
a process that cannot occur spontaneously
Consider the conversion of a substance from solid to liquid.
Solid
Liquid
At one atmosphere pressure and at the melting point of the substance, ____.
a. H = 0 for the process
b. S = 0 for the process
c. E = 0 for the process
d. G = 0 for the process
e. both H = 0 and E = 0 for the process
____
Estimate the temperature at which G = 0 for the following reaction.
NH3(g) + HCl(g)  NH4Cl(s)
H = 176 kJ;
S = 284.5 J/K
41.
a.
b.
c.
d.
e.
467 K
582 K
619 K
634 K
680 K
____
42.
For a certain process at 127C, G = 16.20 kJ and H = 17.0 kJ. What is the entropy change for
this process at this temperature? Express your answer in the form, S = ____ J/K.
a. 6.3 J/K
b. +6.3 J/K
c. 2.0 J/K
d. +2.0 J/K
e. 8.1 J/K
____
43.
One of the reactions that is used to produce gaseous hydrogen commercially follows. A proper
expression for the rate of this reaction could be ____.
H2O(g) + CO(g)  H2(g) + CO2(g)
a.
b.
c. k
d.
e.
____
44.
Consider the exothermic combustion of coal. Which of the following could increase the rate of
reaction?
a. using smaller pieces of coal
b. increasing the concentration of oxygen
c. lowering the temperature
d. both (a) and (b) are correct
e. choices (a), (b) and (c) are all correct
____
45.
A reaction A + 2B  C is found to be first order in A and first order in B. What are the units of the
rate constant, k, if the rate is expressed in units of moles per liter per minute?
a. M1min1
b. M
c. Mmin1
d. min1
e. M2min1
____
46.
The gas-phase reaction
2NO + 2H2  N2 + 2H2O
has the following rate law expression, rate = 0.14 L2/mol2s[NO]2[H2]. If the [NO] is 0.95 M and the [H2] is
0.45 M, what rate is expected?
a. 0.060 mol/Ls
b. 0.43 mol/Ls
c. 0.027 mol/Ls
d. 1.54 mol/Ls
e. 0.057 mol/Ls
____
47.
Evaluate the specific rate constant for the reaction at the temperature for which the data were
obtained. The rate-law expression is rate = k[A][B]2.
A+BC
Experiment
1
2
3
a.
b.
c.
d.
e.
____
Initial [B]
0.10 M
0.20 M
0.20 M
Initial Rate of Formation of C
4.0  104 M/min
3.2  103 M/min
1.6  103 M/min
1.2  102 M2min1
3.6  102 M2min1
4.0  101 M2min1
6.2  101 M2min1
7.0  103 M2min1
48.
The half-life of the zero order reaction below is 0.56 minutes. If the initial concentration of A is 3.4
M, what is the rate constant?
AB
a.
b.
c.
d.
e.
____
Initial [A]
0.10 M
0.20 M
0.10 M
49.
6.07 mol/Lmin
1.24 mol/Lmin
3.04 mol/Lmin
0.619 mol/Lmin
1.79 mol/Lmin
The second order reaction below has a rate constant of 5.76 M1min1 at 1600 K.
2CH4  C2H2 + 3H2
How long would it take for the concentration of CH4 to be reduced from 0.89 M to 5.25  104 M?
a. 165 hrs
b. 0.15 hrs
c. 2.75 hrs
d. 5.51 hrs
e. 9.27 hrs
____
50.
Which of the following statements regarding collision and transition state theory is false?
a. Reactants must collide to form products.
b.
c.
d.
e.
____
All reactant collisions result in product formation.
Activation energy is always positive.
Reactant molecules must absorb energy to form the transition state.
Reactant collisions must be oriented properly to form products.
51.
A reaction has an activation energy of 40 kJ and an overall energy change of reaction of 100 kJ. In
each of the following potential energy diagrams, the horizontal axis is the reaction coordinate and the vertical
axis is potential energy in kJ. Which potential energy diagram best describes this reaction?
a.
b.
c.
d.
e.
____
52.
Reaction rates increase with increasing temperature because ____.
a. the activation energy increases
b. larger molecules collide more frequently
c. the energy of the transition state is lowered
d. the activation energy is decreased
e. a greater fraction of molecules possess the activation energy when they collide
____
____
53.
The specific rate constant, k, for a reaction is 0.44 s1 at 298 K, and the activation energy is
245.kJ/mol. Calculate k at 398 K. (The universal gas constant = 8.314 J/molK.)
a.
b.
c.
d.
e.
2.71  1010 s1
6.17  1010 s1
1.03  1010 s1
8.32  108 s1
4.51  109 s1
54.
a.
b.
c.
d.
e.
A catalyst ____.
is used up in a chemical reaction
changes the value of G0 of the reaction
is always a solid
does not influence the reaction in any way
changes the activation energy of the reaction
Pretest 1
Answer Section
MULTIPLE CHOICE
1.
ANS:
A
PTS:
1
DIF:
TOP: Some Thermodynamic Terms
2.
ANS:
C
PTS:
1
TOP:
3.
ANS:
C
PTS:
1
TOP:
4.
ANS:
B
PTS:
1
TOP:
5.
ANS:
C
PTS:
1
TOP:
6.
ANS:
A
PTS:
1
TOP:
7.
ANS:
E
PTS:
1
TOP:
8.
ANS:
A
PTS:
1
TOP:
9.
ANS:
A
PTS:
1
TOP:
10.
ANS:
E
PTS:
1
TOP:
Delta H°f
11.
ANS:
B
PTS:
1
TOP:
12.
ANS:
D
PTS:
1
TOP:
13.
ANS:
A
PTS:
1
TOP:
14.
ANS:
E
PTS:
1
TOP:
15.
ANS:
A
PTS:
1
TOP:
16.
ANS:
A
PTS:
1
TOP:
17.
ANS:
B
PTS:
1
TOP:
18.
ANS:
D
PTS:
1
TOP:
19.
ANS:
C
PTS:
1
TOP:
Spontaneity
20.
ANS:
A
PTS:
1
TOP:
Spontaneity
21.
ANS:
D
PTS:
1
TOP:
Spontaneity
22.
ANS:
C
PTS:
1
TOP:
Spontaneity
23.
ANS:
B
PTS:
1
TOP:
24.
ANS:
E
PTS:
1
TOP:
25.
ANS:
C
PTS:
1
TOP:
Law Expression
26.
ANS:
B
PTS:
1
TOP:
Law Expression
27.
ANS:
B
PTS:
1
TOP:
Law Expression
28.
ANS:
A
PTS:
1
TOP: Concentration Versus Time: The Integrated Rate Equation
29.
ANS:
A
PTS:
1
TOP: Concentration Versus Time: The Integrated Rate Equation
30.
ANS:
A
PTS:
1
TOP: Concentration Versus Time: The Integrated Rate Equation
Harder Question
Enthalpy Changes
Changes in Internal Energy, Delta E
Calorimetry
Calorimetry
Thermochemical Equations
Hess's Law
Hess's Law
Bond Energies
Standard Molar Enthalpies of Formation,
Relationship Between Delta H and Delta E
Entropy, S, and Entropy Change, Delta S
Hess's Law
Relationship Between Delta H and Delta E
Entropy, S, and Entropy Change, Delta S
Entropy, S, and Entropy Change, Delta S
Entropy, S, and Entropy Change, Delta S
The Second Law of Thermodynamics
The Temperature Dependence of
Free Energy Change, Delta G, and
Free Energy Change, Delta G, and
The Temperature Dependence of
The Rate of a Reaction
Nature of the Reactants
Concentrations of Reactants: The RateConcentrations of Reactants: The RateConcentrations of Reactants: The Rate-
31.
ANS:
C
PTS:
1
TOP:
32.
ANS:
B
PTS:
1
TOP:
33.
ANS:
B
PTS:
1
TOP:
Expression
34.
ANS:
E
PTS:
1
TOP:
35.
ANS:
D
PTS:
1
TOP:
36.
ANS:
E
PTS:
1
TOP:
37.
ANS:
D
PTS:
1
TOP:
38.
ANS:
E
PTS:
1
TOP:
39.
ANS:
A
PTS:
1
TOP:
40.
ANS:
D
PTS:
1
TOP:
Spontaneity
41.
ANS:
C
PTS:
1
TOP:
Spontaneity
42.
ANS:
C
PTS:
1
TOP:
Spontaneity
43.
ANS:
E
PTS:
1
TOP:
44.
ANS:
D
PTS:
1
TOP:
45.
ANS:
A
PTS:
1
TOP:
Law Expression
46.
ANS:
E
PTS:
1
TOP:
Law Expression
47.
ANS:
C
PTS:
1
TOP:
Law Expression
48.
ANS:
C
PTS:
1
TOP: Concentration Versus Time: The Integrated Rate Equation
49.
ANS:
C
PTS:
1
TOP: Concentration Versus Time: The Integrated Rate Equation
50.
ANS:
B
PTS:
1
TOP:
51.
ANS:
A
PTS:
1
TOP:
52.
ANS:
E
PTS:
1
TOP:
53.
ANS:
A
PTS:
1
TOP:
54.
ANS:
E
PTS:
1
TOP:
Temperature: The Arrhenius Equation
Catalysts
Reaction Mechanisms and the Rate-Law
Collision Theory of Reaction Rates
The First Law of Thermodynamics
Thermochemical Equations
Changes in Internal Energy, Delta E
Changes in Internal Energy, Delta E
Entropy, S, and Entropy Change, Delta S
Free Energy Change, Delta G, and
The Temperature Dependence of
The Temperature Dependence of
The Rate of a Reaction
Nature of the Reactants
Concentrations of Reactants: The RateConcentrations of Reactants: The RateConcentrations of Reactants: The Rate-
Transition State Theory
Transition State Theory
Temperature: The Arrhenius Equation
Temperature: The Arrhenius Equation
Catalysts