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AP Unit 8 Review

Total questions: 187

Worksheet time: 2hrs 25mins

Name
Class
Date
1.

Step 1: NO(g)  +  O3(g)   -->  NO2(g)  +  O2(g)

Step 2:  NO2(g)  +  O(g)  --> NO(g)  +  O2(g)

A reaction mechanism for the destruction of ozone, O3(g), is represented above. In the overall reaction, NO(g) is best described as

a)

an inhibitor

b)

a catalyst

c)

a reactant

d)

an intermediate

e)

a product

2.

2A(g)  +  B(g)  --> 2C(g)   When the concentration of substance B in the reaction is doubled, all other factors being held constant, it is found that the rate of the reaction remains unchanged.  The most probably explanation for this observation is that:

a)

A)   The order of the reaction with respect to substance B is 1

b)

A)   Substance B is not involved in any of the steps in the mechanism of the reaction

c)

A)   Substance B is not involved in the rate-determined step of the mechanism, but is involved in subsequent steps

d)

A)   Substance B is probably a catalyst, and as such, its effect on the rate of the reaction does not depend on its concentration

3.

Step 1: Ce4+ + Mn2+  -->  Ce3+  +  Mn3+

  Step 2: Ce4+ + Mn3+  -->  Ce3+  +  Mn4+

Step 3: Mn4+ + Tl+  -->  Tl3+  +  Mn2+

The proposed steps for a catalyzed reaction between Ce4+ and Tl+ are represented above. The products of the overall catalyzed reaction are:

a)

Ce4+ and Tl+

b)

Ce3+ and Tl3+         

c)

Ce3+ and Mn3+           

d)

Ce3+ and Mn4+          

e)

Tl3+ and Mn2+  

4.

NO2(g)  +  CO(g)  -->  NO(g)  +  CO2(g)  

The reaction between NO2(g) and CO(g) is represented above. The elementary steps of a proposed reaction mechanism are represented below.

Step 1:  2NO2(g)  -->  NO(g)  +  NO3(g)                           (slow)

 Step 2:  NO3(g)  +  CO(g)  -->  NO2(g)  +  CO2(g)            (fast)

 

            Which of the following is the rate law for the overall reaction that is consistent with the proposed mechanism?

a)

Rate = k [NO2] [CO]        

b)

Rate = k [NO2]2      

c)

Rate = k [NO3] [CO]       

d)

Rate = k [NO2] [NO3] [CO]

5.

Br2(g)  +  2NO(g)  -->  2NOBr(g)

The reaction represented by the equation above has the following proposed mechanism

 

                        Step 1:   NO(g)  +  Br2(g)  <-->  NOBr2(g)             (fast)

                        Step 2:   NOBr2(g)  +  NO(g)  -->  2NOBr(g)       (slow)

Based on the information, which of the following is the initial rate law for the reaction?

a)

Rate = k[Br2] [NO]         

b)

Rate = k[Br2] [NO]2       

c)

Rate = k[Br2]2 [NO]       

d)

Rate = k[NOBr2] [NO]

6.

2H2(g)  +  2NO(g)  ®  N2(g)  +  2H2O(g)The experimental rate law for the reaction represented above is rate = k[H2][NO]2. Which of the following proposed mechanisms is consistent with the rate law?

a)
b)
c)
d)
7.

Although the combustion of methane is a spontaneous process, a spark must be introduced in order to trigger the reaction. Which of the following statements provides the best explanation for why this is so?

a)

The spark provides the activation energy required to get the reaction started

b)

The hot chemicals from the flint catalyze the reaction

c)

The heat from the spark increases the activation energy for the reaction

d)

The heat from the spark decreases DE, making the reaction less exothermic

e)

The heat from the spark removed energy from the bonds in the methane molecules, thereby lowering the activation energy for the forward reaction.

8.

Which of the following statements are associated with fast reaction rates?

I. Reactant molecules with weak bonds

II. High activation energy

III. A high percentage of collision orientations that can produce a reaction

a)

I only

b)

II only

c)

I and II only

d)

I and III only

e)

I, II, and III

9.

Which of the following must be true for a reaction for which the activation energy is the same for both the forward and the reverse reaction?

a)

A catalyst is present

b)

The reaction order can be obtained directly from the balanced equation

c)

The reaction order is zero

d)

Δ\Delta S for the reaction is zero

e)

Δ\Delta H for the reaction is zero

10.

What is collision theory?

a)

Molecules must collide in the correct orientation with enough energy to bond.

b)

Molecules need enough energy to collide and react.

c)

Atoms constantly collide and react.

d)

The minimum energy needed for atoms to react

11.

What is the rate of reaction?

a)

How much energy is needed for a reaction to occur.

b)

The energy required to break a bond.

c)

The time it takes for a reaction to occur.

d)

Collision Theory

12.

Increasing the temperature of your solution will.......

a)

Not affect the rate of reaction.

b)

Speed up the rate of reaction

c)

Slow down the rate of reaction

13.

Which has more surface area?

a)

Large chunks of chalk

b)

Cube of sugar

c)

Powdered sugar

d)

Small chunks of sugar

14.

If you shrink the container size that your gas substance is in what will happen?

a)

The reaction rate will stay the same

b)

The reaction rate will speed up

c)

The reaction rate will slow down

15.
If the reactant particles collide with less than the activation energy, the particles will be rebound, and no reaction will occur.
a)
True
b)
False
16.
With the increase in temperature, the average kinetic energy of the molecules increases, leading to a decrease in number of collisions per unit time.
a)
True
b)
False
17.
The collisions which bring about a chemical reaction are called: 
a)
Consistent collisions
b)
 Normal collisions 
c)
Effective collisions 
d)
None of the above
18.
More collisions correspond to a: 
a)
Faster reaction rate  
b)
Slower reaction rate
c)
Constant reaction rate 
d)
None of the above
19.

Which of the following is/are the fundamental idea(s) of collision theory?

a)

Molecules react by colliding together

b)

The effective collisions must occur with certain minimum amounts of energy

c)

In a large sample, the greater the number of effective collisions, and the faster the rate of reaction

d)

All of these are correct

20.
Which factors increase the rate of a reaction.
a)
increasing temperature
b)
increasing concentration
c)
increasing surface area
d)
all of these
21.

How could we make this reaction happen more quickly?

a)

Decrease the concentration of the acid

b)

crush the chalk to increase the surface area

c)

Put the test tube in an ice bath

22.

When surface area is decreased the rate of reaction...

a)

Decreases, because there are LESS possible sites for correct collisions

b)

Increases, because there are LESS possible sites for correct collisions

c)

Decreases, because there are MORE possible sites for correct collisions

d)

Increases, because there are MORE possible sites for correct collisions

23.

A temperature increase causes the particles ......

a)

to slow down

b)

move faster

c)

collide higher

d)

in the right order

24.

How does a catalyst work in speeding up a reaction?

a)

By lowering the activation energy or reaction

b)

by giving them more energy

c)

by making them more available

25.

Which PE Diagram represents an endothermic reaction?

a)

A

b)

B

26.

Which PE Diagram represents an exothermic reaction?

a)

A

b)

B

27.

Decreasing the concentration of a substance will usually........

a)

Slow down the reaction

b)

Speed up the reaction

c)

Have no affect on the reaction

28.
Which factors increase the rate of a reaction.
a)
increasing temperature
b)
increasing concentration
c)
increasing surface area
d)
all of these
29.
Why does a higher temperature increase the rate of a reaction?
a)
it increases both the frequency and energy of particle collisions
b)
it only increases the frequency of particle collisions
c)
it only increases the energy of particle collisions
d)
it reduces the activation energy of the reaction
30.
Which of the following is NOT a factor affecting reaction rate?
a)
temperature
b)
catalysts
c)
particle size
d)
polarity
31.
What is the catalyst in the following rate mechanism?
a)
HBr
b)
H2O
c)
There is no catalyst
32.
How many intermediates are in the following rate mechanism?
a)
0
b)
1
c)
2
d)
3
33.
How many elementary steps are in the following reaction
a)
1
b)
2
c)
3
34.
Which is the rate determining step?
a)
1
b)
2
c)
3
35.
Which of the elementary steps  has the highest activation energy?
a)
slow
b)
fast
36.
Which step does a catalyst affect?
a)
slow 
b)
fast
37.

If there is only single substance (atom, molecule, or ion) involved in the rate-determining step, that reaction is said to be

a)

unimolecular

b)

bimolecular

c)

polimolecular

d)

trimolecular

38.

If there is two substances (atom, molecule, or ion) involved in the rate-determining step, that reaction is said to be

a)

unimolecular

b)

bimolecular

c)

trimolecular

d)

polimolecular

39.

Reaction :


2A + B → C + D


is proposed to have reaction mechanism shown below :


A + B → AB + D (slow)

A + AB → C (fast)


the consistent rate equation with the reaction mechanism above is ____

a)

rate = k [A]2 [B]

b)

rate = k [A]2 [B]2

c)

rate = k [A] [B]

d)

rate = k [A] [B]2

40.

The decomposition of nitrous oxide :


2N2O(g) → 2N2(g) + O2(g)


is believed to occur by two-step mechanism


N2O(g) → N2(g) + O(g) (slow)

N2O(g) + O(g) → N2(g) + O2(g) (fast)


the consistent rate equation based on the mechanism above is ____

a)

rate = k [N2O]2

b)

rate = k [N2O]

c)

rate = k [N2O]2 [N2]

d)

rate = k

41.

In an endothermic reaction....

a)

The products have more energy then the reactants.

b)

The reactants have more energy then the products.

42.
Which trials would be used to measure the rate exponent for A?
a)
trials 1 and 2
b)
trials 1 and 3
c)
trials 2 and 3
43.
Which trials would be used to find the rate exponent for B
a)
trials 1 and 2
b)
trials 1 and 3
c)
trials 2 and 3
44.
What is the rate exponent for A?
a)
0
b)
1
c)
2
45.
What is the rate exponent for B?
a)
0
b)
1
c)
2
46.
Which trial do you insert into the rate law to find k (rate = k [A]m[B]n)?
a)
trial 1
b)
trial 2
c)
trial 3
d)
any trial will work
47.

Which of the following processes involves the greatest increase in entropy?

a)

SO3(g) + H2(g) --> SO2(g) + H2O(g)

b)

N2(g) + 3H2(g) --> 2NH3(g)

c)

Ag+(aq) + Cl-(aq) --> AgCl(s)

d)

C2H2(g) + 2H2(g) --> C2H6(g)

e)

MgSO3(s) --> MgO(s) + SO2(g)

48.

A student observes the equilibrium constant for a reaction is greater than 1.0 at temperatures below 500 K but less than 1.0 at temperatures above 500 K. What can the student conclude about the values of Δ\Delta H° and Δ\Delta S° for the reaction? (Assume that Δ\Delta H° and Δ\Delta S° are independent of temperature.)

a)

Δ\Delta H° > 0 and  Δ\Delta  S° > 0     

b)

Δ\Delta H° > 0 and  Δ\Delta  S° < 0      

c)

Δ\Delta  H° < 0 and  Δ\Delta  S° > 0    

d)

Δ\Delta  H° < 0 and  Δ\Delta  S° < 0

49.

In which of the following processes will Δ\Delta S° be negative?

a)

C2H5OH(l)  -->  C2H5OH(g)  

b)

NaCl(s)  -->  NaCl(l)

c)

CO2(s)  -->  CO2(g)

d)

Cl2(g)  -->  Cl2(l)

50.

Which of the following particulate representations shows a process during which the entropy of the system decreases?

a)
b)
c)
d)
51.

When solid ammonium chloride, NH4Cl(s), is added to water at 25°C, it dissolves and the temperature of the solution decreases. Which of the following is true for the values of Δ\Delta  H and Δ\Delta  S for the dissolving process?

a)

Δ\Delta  H = positive

Δ\Delta  S = positive

b)

Δ\Delta  H = positive

Δ\Delta  S = negative

c)

Δ\Delta  H = positive

Δ\Delta  S = equal to zero

d)

Δ\Delta  H = negative

Δ\Delta  S = positive

e)

Δ\Delta  H = negative

Δ\Delta  S = negative

52.

CH3OH(g)  --> CO(g) + 2H2(g)      Δ\Delta  H° = +91 kJ/molrxn

The reaction represented above goes essentially to completion. The reaction takes place in a rigid, insulated vessel that is initially at 600 K. What can be inferred about Δ\Delta  S° for the reaction at 600 K?

a)

It must be positive, since the reaction is thermodynamically unfavorable at 600 K.

b)

It must be negative, since there are more moles of products than reactants

c)

It must be positive, since Δ\Delta  G° is negative and Δ\Delta  H° is positive

d)

It must be negative, since Δ\Delta  G° is positive and Δ\Delta  H° is positive

53.

The equilibrium constant for a reaction is greater than 1.0 at temperatures above 500 K but less than 1.0 at temperatures below 500 K. What can be concluded about the values of Δ\Delta H° and Δ\Delta S° for the reaction? (assume that Δ\Delta H° and Δ\Delta S° are independent of temperature)

a)

Δ\Delta H° > 0 and Δ\Delta S° > 0       

b)

Δ\Delta H° > 0 and Δ\Delta S° < 0     

c)

Δ\Delta H° < 0 and Δ\Delta S° > 0     

d)

Δ\Delta H° < 0 and Δ\Delta S° < 0    

54.

2PCl3(g)  +  O2(g)   -->    2POCl3(g)

The oxidation of PCl3(g) is represented by the equation above and the table provides the approximate values of the absolute molar entropies for these substances. Based on the information given, what is the approximate Δ\Delta S° for the reaction?

a)

+170 J/(molrxn×K)         

b)

-170 J/(molrxn×K) 

c)

+190 J/(molrxn×K) 

d)

-190 J/(molrxn×K) 

55.

XY2 --> X + Y2

The equation above represents the decomposition of a compound XY2. The diagram shows two reaction profiles (path one and path two) for the decomposition of XY2.  The reaction is thermodynamically favorable under standard conditions at 298 K. Therefore, the value of Δ\Delta S° for the reaction must be

a)

equal to zero

b)

equal to Δ\Delta H°         

c)

greater than Δ\Delta

d)

less than Δ\Delta

56.

What is the general relationship between temperature and entropy for diatomic gases?

a)

They are completely independent of each other; temperature has no effect on entropy

b)

There is a direct relationship because at higher temperatures there is an increase in energy dispersal

c)

There is an inverse relationship because at higher temperatures substances are more likely to be in a gas state

d)

It depends on the specific gas and the strength of the intermolecular forces between individual molecules

57.

What is the symbol for entropy?

a)

H

b)

G

c)

S

d)

E

58.

Entropy is a measure of

a)

accuracy

b)

precision

c)

the disorder of a system

d)

the attraction of a nucleus for an electron

59.

Which of these processes represents a decrease in entropy?

a)

sublimation of CO2

b)

boiling water

c)

condensation of steam on cold glass

d)

NaCl dissolving in water

60.

Which of these reactions shows a DECREASE in entropy?

a)

CaCO3(s) → CaO(s) + CO2(g)

b)

3O2(g) → 2O3(g)

c)

2NH3(g) → 3H2(g) + N2(g)

d)

C6H6(l) → C6H6(g)

61.

The entropy will usually increase when

a)

a molecule is broken into two or more smaller molecules

b)

a reaction occurs that results in an increase in the number of moles of gas

c)

a solid changes to a liquid

d)

all of these

62.

Which reaction has a +ΔS ?

a)

AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)

b)

H2O(g) + CO2(g) → H2CO3(aq)

c)

H2(g) + I2(g) → 2Hl(g)

d)

C2H2O2(g) → 2CO(g) + H2(g)

63.

Systems in nature tend to undergo changes toward

a)

lower energy and less disorder

b)

lower energy and more disorder

c)

higher energy and less disorder

d)

higher energy and more disorder

64.

Which sample has the lowest entropy?

a)

1 mole of KNO3(l)

b)

1 mole of KNO3(s)

c)

1 mole of H2O(l)

d)

1 mole of H2O(g)

65.

Entropy increases from solid, liquid to gas. Why?

a)

Molecular disorder increases

b)

Molecules increase in number from solid to gas

c)

Molecules are heavier in solid

d)

Molecules are more reactive

66.

Which state of matter has the greatest motion and least orderly arrangement?

a)

solid

b)

liquid

c)

gas

d)

aqueous

67.
Entropy always increases when
a)
enthalpy decreases.
b)
temperature decreases.
c)
temperature increases.
d)
volume increases.
68.

Entropy of a system increases when a reaction increases the number of particles.

a)

True

b)

False

69.

Which of the reactions below has a negative ∆S?

a)

CuCO3 (s) + 2HCl (aq) → CuCl2 (aq) + CO2 (g) + H2O (l)

b)

C (s) + O2 (g) → CO2 (g)

c)

CuO (s) + H2SO4 (aq) → CuSO4 (aq) + H2O (l)

d)

BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl (aq)

70.

What is a spontaneous process ?

a)

slow process

b)

fast process

c)

process that needs an external intervention to occur

d)

process that does not need external intervention to occur / keep happening

71.

Which of the following is non-spontaneous?

a)

Evaporating Water

b)

Cooling down of hot water

c)

Condensing Water Vapor

d)

Solidifying of Magma

72.

Which of the following is a spontaneous process will give the lowest entropy after the process?

a)

Evaporating Water

b)

Cooling down of hot water

c)

Condensing Water Vapor

d)

Solidifying of Magma

73.

When gases are produced, Entropy is ____________.

a)

Greater than zero

b)

Lesser than zero

c)

Equal to zero

d)

Entropy wiill not be equal to zero, so its either of the two.

74.
Predict the entropy change and its spontaniety
a)

ΔS = +ve and non spontaneous

b)
ΔS = -ve and spontaneous
c)
ΔS = -ve and non spontaneous
d)
ΔS = +ve and spontaneous
75.
Predict the entropy change and its spontaniety
a)
ΔS = +ve and non spontaneous
b)
ΔS = -ve and spontaneous
c)
ΔS = -ve and non spontaneous
d)
ΔS = +ve and spontaneous
76.
Predict the entropy change and its spontaniety
a)
ΔS = +ve and non spontaneous
b)
ΔS = -ve and spontaneous
c)
ΔS = -ve and non spontaneous
d)
ΔS = +ve and spontaneous
77.
Predict the entropy change, ΔS.
a)
ΔS = +ve
b)
ΔS = -ve
c)
ΔS = 0
d)
ΔS = no change
78.
Predict the entropy change, ΔS.
a)
ΔS = +ve
b)
ΔS = -ve
c)
ΔS = 0
d)
ΔS = no change
79.
Predict the entropy change, ΔS.
a)
ΔS = +ve
b)
ΔS = -ve
c)
ΔS = 0
d)
ΔS = little change
80.

A small S value indicates the system has _______

a)

more order

b)

more randomness

81.

Identify whether the following result in an increase or decrease in entropy:


3 moles of gas (on reactant side) --> 6 moles of gas (product)

a)

increase

b)

decrease

82.

Which represents a -ΔS?

a)

ice melting

b)

salt dissolving

c)

water heating up

d)

none of these

83.

Which of the following scenarios describes a process with a negative entropy change?

a)

Building a skyscraper

b)

A clean room becomes cluttered

c)

An igloo melting

d)

Osmosis (I hope you know your Biology!)

84.

Which combination of ΔH and ΔS always has a spontaneous reaction?

a)

+ΔH and +ΔS

b)

+ΔH and -ΔS

c)

-ΔH and -ΔS

d)

-ΔH and +ΔS

85.

Which combination of ΔH and ΔS NEVER has a spontaneous reaction?

a)

+ΔH and +ΔS

b)

+ΔH and -ΔS

c)

-ΔH and -ΔS

d)

-ΔH and +ΔS

86.
Spontaneous reactions may be extremely slow.
a)
True
b)
False
87.
Reactions tend to be spontaneous if they are exothermic.
a)
True
b)
False
88.

Which substance would likely have the greater entropy?

a)

SO3(g)

b)

SO2(g)

89.

Which substance would likely have the greater entropy?

a)

Br2(l)

b)

Br2(g)

90.

Which Substance would likely have the greater entropy?

a)

Sn(s)

b)

Pb(s)

91.

For the reaction: 2NH3(g) --> N2(g) + 3H2(g)

a)

Entropy is increasing in the forward direction

b)

Entropy is decreasing in the forward direction

92.

For the reaction: NOCl2(g) + NO(g) ---> 2NOCl(g)

a)

Entropy increases in the forward direction

b)

Entropy decreases in the forward direction

93.

2NH3(g) + 5O2(g) ---> 4NO(g) + 6H2O(g), ΔH=-907.2kJ/mol

a)

Equilibrium is achieved with a reasonable amount of reactants and products

b)

Equilibrium goes almost to completion

c)

Equilibrium virtually does not occur

94.

N2(g) + 2O2(g) ---> 2NO2(g), ΔH= 68kJ /mol

a)

will achieve equilibrium with a reasonable amount of reactants and products

b)

Will go almost to completion

c)

Will virtually not ocur

95.

S(s) + O2(g) ----> SO2(g) ΔH= -297 kJ/mol

a)

reaction achieves equilibrium with a reasonable amount of reactants and products

b)

reaction virtually does not occur

c)

reaction goes virtually to completion

96.

N2(g)  +  3H2(g) <-->  2NH3(g)      Δ\Delta298 = -92 kJ/molrxn        Δ\Delta298 = -33 kJ/molrxn

Consider the reaction represented above at 298 K. When equal volumes of N2(g) and H2(g), each at 1 atm, are mixed in a closed container at 298 K, no formation of NH3(g) is observed. Which of the following best explains the observation.

a)

The N2(g) and the H2(g) must be mixed in a 1:3 ratio for a reaction to occur

b)

A high activation energy makes the forward reaction extremely slow at 298 K

c)

The reaction has an extremely small equilibrium constant, thus almost no product will form

d)

The reverse reaction has a lower activation energy than the forward reaction, so the forward reaction does not occur

97.

H(g) + Cl(g)  --> HCl(g)

The formation of HCl(g) from its atoms is represented by the equation above. Which of the following best explains why the reaction is thermodynamically favored?

a)

Δ\Delta G° > 0 because energy is released as the bond between H and Cl atoms forms, and entropy increases because the number of gaseous product particles is less than the number of gaseous reactant particles.

b)

Δ\Delta  G° > 0 because energy is absorbed as the bond between H and Cl atoms forms, and entropy decreases because the number of gaseous product particles is less than the number of gaseous reactant particles.

c)

Δ\Delta  G° < 0 because energy is absorbed as the bond between H and Cl atoms forms, and entropy increases because the number of gaseous product particles is less than the number of gaseous reactant particles.

d)

Δ\Delta  G° < 0 because although entropy decreases because the number of gaseous product particles is less than the number of gaseous reactant particles, energy is released as the bond between the H and Cl atoms forms.

98.

2H2O2(aq)  -->  2H2O(l)  +  O2(g)         Δ\Delta  G°rxn = -234 kJ/molrxn

The value of Δ\Delta G° for the reaction represented above implies that the decomposition of H2O2(aq) is thermodynamically favorable. However, H2O2(aq) is typically stable for up to a year stored in a dark bottle at 298 K. The best explanation for this observation is that the decomposition reaction:

a)

Is only thermodynamically favorable in the presence of a catalyst

b)

Occurs with an increase in entropy because O2(g) is a product

c)

Is reversible and H2O2(aq) is produced almost as fast as it decomposes

d)

Has a slow rate at 298 K because the activation energy is relatively high

99.

HA(aq) + H2O(l) <--> A-(aq) + H3O+(aq)      Δ\Delta G° = +35 kJ/molrxn       

Based on the chemical equation and Δ\Delta G° given above, which of the following justifies the claim that HA(aq) is a weak acid?

a)

Because Δ\Delta G° > 0, Ka > 1, and HA completely dissociates

b)

Because Δ\Delta G° > 0, Ka > 1, and HA almost completely dissociates

c)

Because Δ\Delta G° > 0, Ka < 1, and HA only partially dissociates

d)

Because Δ\Delta G° > 0, Ka < 1, and HA does not dissociate

100.

N2(g)  +  3H2(g)  <-->  2NH3(g)

K = 5.6 x 105 at 298 K             Δ\Delta  rxn = -91.8 kJ/molrxn

The synthesis of NH3 is represented by the equation above. Based on the equilibrium constant, K, and H°rxn given above, which of the following can best be used to justify that the reaction is thermodynamically favorable at 298 K and constant pressure?

a)

Δ\Delta G° = -RTlnK > 0 because K > 1         

b)

Δ\Delta G° = -RTlnK < 0 because K > 1  

c)

Δ\Delta G° = Δ\Delta H° - T Δ\Delta S° < 0 because Δ\Delta H° < 0 and Δ\Delta S° > 0

d)

Δ\Delta G° = Δ\Delta H° - T Δ\Delta S° > 0 because Δ\Delta H° < 0 and Δ\Delta S° < 0

101.

As a sample of KNO3(s) is stirred into water at 25°C, the compound dissolves endothermically. Which of the following best helps to explain why the process is thermodynamically favorable at 25°C?

a)

All endothermic processes are thermodynamically favorable

b)

Stirring the solution during dissolution adds the energy needed to drive an endothermic process

c)

Dissolving the salt decreases the enthalpy of the system

d)

Dissolving the salt increases the enthalpy of the system

102.

The table lists the equilibrium constants and changes in thermodynamic properties for the dissolution of FeCO3 and MnCO3 at 25°C. The two particle diagrams represent saturated solutions of each compound at equilibrium. Which of the following explains which of the properties listed in the table is best represented by the particle diagram?

a)

The particle diagrams best represent that Δ\Delta H° < 0 because the ions from both compounds are solvated by water molecules

b)

The particle diagrams best represent that Δ\Delta H° < 0 because both compounds produce about the same amount of CO32-ions from the dissolution

c)

The particle diagrams best represent that Δ\Delta S° > 0 because both compounds produce a very small amount of ions from the dissolution

d)

The particle diagram best represent that the molar solubility is greater for FeCO3 compared to MnCO3

103.

High solubility of an ionic solid in water is favored by which of the following conditions?

                        I.  The existence of strong ionic attractions in the crystal lattice

                        II.  The formation of strong ion-dipole attractions

                        III. An increase in entropy upon dissolving

a)

I only

b)

I and II only

c)

I and III only

d)

II and III only

e)

I, II, and III

104.

What does Gibbs Free Energy tell us?

a)

How much energy is given off by a reaction.

b)

The tendency of a reaction to become "random"

c)

How spontaneous a reaction is.

105.

What information do we need to perform a calculation of Gibbs Free Energy?

a)

Enthalpy of the reaction.

b)

Entropy of the reaction.

c)

The temperature of the reaction in Kelvin.

d)

All of the above are needed.

106.

Which of the following would most likely lead to a spontaneous reaction.

a)

A high negative enthalpy.

b)

A low negative enthalpy.

c)

A high positive enthalpy.

d)

A low positive enthalpy.

107.

Your enthalpy is +20 and your entropy is +5. Which temperature will give a spontaneous reaction?

a)

0

b)

4

c)

8

108.

Your enthalpy is high and negative but your entropy is also negative. What type of temperature would you want to get a spontaneous reaction?

a)

low

b)

high

109.

Your enthalpy is positive and your entropy is positive. What type of temperature would you want to ensure a spontaneous reaction.

a)

very high

b)

very low

110.

Which combination of ΔH and ΔS NEVER has a spontaneous reaction?

a)

+ΔH and +ΔS

b)

+ΔH and -ΔS

c)

-ΔH and -ΔS

d)

-ΔH and +ΔS

111.

Your enthalpy is -20 and your entropy is -8. Which temperature will give you a spontaneous reaction?

a)

1

b)

3

c)

5

112.

6. The formation ½ A2 + 2 B2 + C --> CAB4 has an enthalpy of formation of -104 kJ and a change in entropy of -60.8 J/K at 30 °C. What is the free energy and spontaneity of the reaction?

a)

-85.6 kJ, spontaneous

b)

-18.3 kJ, not spontaneous

c)

+18.3 kJ, spontaneous

d)

+85.6 kJ, not spontaneous

113.

For the process at 250C : I2(g) →I2(s). What are the signs for ΔG, ΔH and ΔS?

a)

ΔG + ΔH - ΔS -

b)

ΔG - ΔH - ΔS -

c)

ΔG - ΔH + ΔS +

d)

ΔG - ΔH + ΔS +

114.

Predict the signs of ΔH , ΔS and ΔG for the reaction:

Mg(s) --> Mg(g)

a)

Δ H = - , Δ S = + and Δ G = - (all temperature)

b)

Δ H = + , Δ S = + and Δ G = - (At all temperature)

c)

Δ H = + , Δ S = + and Δ G = - (At low temperature)

d)

Δ H = + , Δ S = + and Δ G = - (At high temperature)

115.

At what temperature would a given reaction become spontaneous if ΔH =+119kJ and ΔS=+263J/K.mol

a)

452 K

b)

2210 K

c)

382 K

d)

363 K

116.
True/False: The rate of a chemical reaction is unrelated to the spontaneity of the reaction.
a)
True
b)
False
117.

1. Given the following information, calculate ΔG0 for the reaction below at 250C: (K = 0C + 273)

SnCl4(l) + 2 H20(l) → SnO2(S) + 4HCl(g),

ΔH0=133.0 kJ and ΔS0 =401.5 J/K

a)

-252.6 kJ

b)

-13.4 kJ

c)

13.4 kJ

d)

252.6 kJ

118.

a)

A

b)

B

c)

C

d)

D

119.

a)

A

b)

B

c)

C

d)

D

120.

a)

A

b)

B

c)

C

d)

D

121.
a)

A

b)

B

c)

C

d)

D

e)

E

122.

A reactionthat is spontaneous at any temperature has a

-------------- entropy and a ---------------- enthalpy.

a)

positive, positive

b)

positive, negative

c)

negative, negative

d)

negative, positive

123.

A reaction that is spontaneous at low temperatures only has a -------------- entropy and a ---------------- enthalpy.

a)

positive, positive

b)

positive, negative

c)

negative, negative

d)

negative, positive

124.

A reaction that is spontaneous at high temperatures only has a -------------- entropy and a ---------------- enthalpy.

a)

positive, positive

b)

positive, negative

c)

negative, negative

d)

negative, positive

125.

A reaction that is not spontaneous any temperatures has a

-------------- entropy and a ---------------- enthalpy.

a)

positive, positive

b)

positive, negative

c)

negative, negative

d)

negative, positive

126.

Free energy change at equilibrium is...

a)

Zero

b)

Positive

c)

Negative

127.

A process will be spontaneous when the change in free energy is...

a)

zero

b)

positive

c)

negative

128.

The SI unit of heat and energy is the __________.

a)

calorie

b)

kelvin

c)

joule

d)

watt

129.
ΔH value in an endothermic reaction is a positive number.
a)
True
b)
False
130.

Δ H is negative indicates that_______.

a)

reaction is exothermic

b)

reaction is endothermic

c)

reaction is spontaneous

d)

reaction is not spontaneous

131.

Δ S is negative indicates that_______.

a)

enthalpy increases

b)

enthalpy decreases

c)

entropy decreases

d)

entropy increases

132.

ΔG is negative indicates that_______.

a)

reaction is exothermic

b)

reaction is endothermic

c)

reaction is spontaneous

d)

reaction is not spontaneous

133.

…………………….occurs naturally and favors the formation of products at the stated conditions

a)

A spontaneous reaction

b)

A nonspontaneous reaction

134.

Spontaneous reactions produce large amounts of products and release free energy.

a)

True

b)

False

135.

A chemical reaction that does not favor the formation of products at the stated conditions is called ……………….

a)

a nonspontaneous reaction.

b)

a spontaneous reaction.

136.

The terms spontaneous and nonspontaneous refer to the rate of a reaction.

a)

True

b)

False

137.

The size and direction of enthalpy changes and entropy changes together do not determine whether a reaction is spontaneous or not.

a)

True

b)

False

138.

Free energy is often expressed as Gibbs free energy.

a)

True

b)

False

139.

The slowest step in a reaction mechanism requires the collision represented above to occur.  Which of the following most likely indicates how the addition of a solid catalyst could increase the rate of the reaction?

a)

The catalyst could change the reaction from second order to third order

b)

The catalyst could increase the particles’ speed, thereby increasing the value of the rate constant, k

c)

The catalyst could decrease the particles’ speed, making it less likely that the particles will rebound without reacting when they collide

d)

The catalyst could absorb one of the particles, making a successful (reaction-producing) collision with the other particle more likely

140.

The energy diagram for the reaction X + Y  --> Z is shown.  The addition of a catalyst to this reaction would cause a change in which of the indicated energy differences?

a)

I only

b)

II only

c)

III only

d)

I and II only

e)

I, II, and III

141.

The energy diagram for the reaction X + Y  --> Z is shown.  At what point on the graph is the activated complex present?

a)

A

b)

B

c)

C

d)

D

e)

none of these

142.

The energy diagram for the reaction X + Y  --> Z is shown.   If the reaction were reversible, would the forward or the reverse have a higher activation energy?

a)

The diagram shows no indication of any activation energy

b)

The forward and reverse activation energies are equal

c)

The forward activation energy would be greater

d)

The reverse activation energy would be greater

e)

none of these

143.

The energy diagram for the reaction X + Y  --> Z is shown.  What would happen if the kinetic energy of the reactants was not enough to provide the needed activation energy?

a)

The products would be produced at a lower energy state

b)

The rate of the reaction would tend to increase

c)

The activated complex would convert into products

d)

The reactants would continue to exist in their present state

e)

The products would form at an unstable energy state

144.

Which of the following reaction energy profiles corresponds to the proposed mechanism?

                        Cl(g)  +  O3(g)  -->  ClO(g)  +  O2(g)       slow step

                        ClO(g)  +  O3(g)   -->  Cl(g)  +  2O2(g)    fast step

                                    2O3(g)  -->  3O2(g)                     overall reaction   Δ\Delta H = -285 kJ/molrxn

a)
b)
c)
d)
145.

O3(g) + O(g)  -->  2O2(g)

The decomposition of O3(g) in the upper atmosphere is represented by the equation above.  The potential energy diagram for the decomposition of O3(g) in the presence and absence of NO(g) is given below. Which of the following mechanisms for the catalyzed reaction is consistent with the equation and diagram above?

a)

2O3(g)  +  2NO(g) -->  4O2(g)  +  N2(g) (slow) 

b)

O3(g) + NO(g) -->  NO2(g) + O2(g) (slow)

NO2(g) + O(g)  -->  NO(g) + O2(g) (fast)

c)

NO2(g) + O3(g)  -->  NO(g) + 2O2(g) (slow)

NO(g)  +  O(g)  -->   NO2(g)  (fast)

d)

NO2(g) + O(g)  -->  NO3(g)  (slow)

NO3(g) + O3(g)  -->  NO2(g) + 2O2(g) (fast)

146.

The diagram above illustrates how the reaction N2(g) + 3H2(g)--> 2NH3(g) occurs on the surface of Ru(s).  The rate of this reaction is determined by the amount of energy required to break the bond in N2. This bond is weakened when N2 is adsorbed on Ru(s). Based on this information, which of the following provides the best reason for the use of Ru(s) for the synthesis of NH3?

a)

It promotes the proper orientation of N and H atoms to form new N-H bonds

b)

It provides a reaction path with a lower activation energy

c)

It forms a bond between Ru and N that is stronger than the bond in N2.

d)

It decreases the frequency of collisions between N2(g) and H2(g)

147.

The energy distribution profile (Curve C) for the Y2 molecules is shown in the graph for the reaction  X + Y2 --> XY2 when it is done under certain experimental conditions.  Line A represents the most probably energy of the Y2 molecules, and Line B represents the activation energy.  Which of the following changes should be made to the graph to explain the increase in the rate of the reaction if the only change in experimental conditions is the addition of a catalyst?

a)

Curve C will broaden and Line B will move to the left, because more Y2 molecules will have an energy greater than the minimum energy needed to overcome the activation energy barrier

b)

Line B will move to the left because a larger fraction of the Y2 molecules will have the minimum energy to overcome the activation energy barrier

c)

Curve C and Line A will move to the right because the average energy of the Y2 molecules will increase

d)

Line A will move to the right because the most probable energy of the Y2 molecules will increase

148.

A reaction profile shows....

a)

the relative difference in temperature of reactants and products

b)

the relative difference in amounts of reactants and products

c)

the relative difference in energy of reactants and products

d)

the relative difference in volume of reactants and products

149.

The minimum energy particles must have to react is the

a)

acting energy

b)

active energy

c)

activation energy

150.

Bond making is

a)

Endothermic

b)

Exothermic

151.

Bond breaking is..

a)

Endothermic

b)

Exothermic

152.

Which letter shows the activation energy

a)

A

b)

B

c)

C

153.

What is the definition of activation energy? Two answers are required.

a)

The energy needed to start a reaction

b)

The temperature needed to start a reaction

c)

The minimum energy that particles must have to react

d)

The maximum energy that particles must have to react.

154.

In a reaction the energy required to break bonds is less than the energy released when bonds are made. What type of reaction is this?

a)

Exothermic

b)

Endothermic

155.

How does a catalyst work in speeding up a reaction?

a)

By lowering the activation energy or reaction

b)

by giving them more energy

c)

by making them more available

156.
Consider the following energy profile diagram for a reaction represented by the equation X+Y→Z
Which one of the following provides the correct values of the activation energy (in kJ mol-1) and the ΔH (in kJ mol-1) for the reaction
a)
Activation Energy = +75; ΔH = +100 
b)
Activation Energy = +100; ΔH = +175
c)
Activation Energy = +175; ΔH = +100
d)
Activation Energy = +200; ΔH = -125
157.
An energy profile for a reversible chemical reaction is shown. According to this profile, the activation energy of the reverse reaction is equal to
a)
D
b)
C - B
c)
A - B
d)
C- D
158.
The energy profiles of two reactions are shown. 
The reaction with the lowest activation energy is
a)
A+B → C+D
b)
X→ Y+Z
c)
C+D → A+B
d)
Z+Y →X
159.

Which letter represents the transition state?

a)

A

b)

B

c)

C

d)

D

e)

E

160.

Illustrated in the reaction profiles are the changes in chemical energy during a range of processes.


Which of the diagrams best describes the changes in chemical energy for a stick of dynamite during an explosion?

a)

a

b)

b

c)

c

161.

The reaction profile for a chemical reaction is shown in the diagram below. Which label corresponds to the change in enthalpy, Δ𝐻,of the reaction?

a)

A

b)

B

c)

C

d)

ALL THE ABOVE

162.
Catalysts permit reactions to proceed along a ___________energy path.
a)
lower
b)
higher
163.
A catalyst increases the efficiency of collisions between reactants.
a)
true
b)
false
164.

Which of the reaction pathway shows the catalysed reaction?

a)

1

b)

2

165.

A catalyst changes the mechanism of the reaction

a)

True

b)

False

166.

What is/are the catalyst(s) in catalytic converters in cars?

a)

Platinum

b)

Phosphorous

c)

Palladium

d)

Phosphorous and platinum

e)

Platinum and palladium

167.

The graph that shows how catalysts lower activation energy is known as what?

a)

Reaction profile

b)

Energy graph

c)

Catalysing reaction graph

d)

Overall change of energy grapg

168.

Which of the following is incorrect for a catalyst?

a)

Bio-chemical reactions are mostly catalysed by enzymes

b)

Catalyst does not start a reaction

c)

Catalyst changes the equilibrium constant of a reaction

d)

Co-enzymes increase the activity of an enzyme

169.

According to adsorption theory of catalysis, the speed of the reaction increases because:

a)

in the process of adsorption, the activation energy of the molecules becomes large.

b)

adsorption produces heat which increases the speed of the reaction

c)

the concentration of the reactant molecules at the active centres of the catalyst becomes high due to adsorption.

d)

adsorption lowers the activation energy of the reaction

170.

How many times can a catalyst be used?

a)

Once - it gets used up in the reaction

b)

A few times

c)

None

d)

Lots of times - it does not get used up in the reaction

171.

True or False : Catalysts remain chemically unchanged at the end of a reaction

a)

True

b)

False

172.
The graph shows a typical energy distribution for particles of an ideal gas in a sealed container at a fixed temperature.   Which of the following statements is true?
a)
Position A represents the mean energy of a molecule in the container.
b)
Addition of a catalyst moves the position of EA to the right.
c)
The area under the curve to the right of EA represents the number of molecules with enough energy to react.
d)
The position of the peak of the curve at a higher temperature is further away from both axes.
173.
a)

Curve II is at the lower temperature and there are less molecules in the sample

b)

Curve II is at the lower temperature and there are the same number of molecules in the sample

c)

Curve II is at the higher temperature and there are more molecules in the sample

d)

Curve II is at the higher temperature and there are the same number of molecules in the sample

174.

Which curve in this Maxwell-Boltzmann distribution represents the highest proportion of particles moving the fastest (# of particles vs. speed)?

a)

Black (peak on the left)

b)

Red (peak in the middle)

c)

Blue (peak on the right)

d)

All particles are moving at the same speed

175.

The question below is about the Maxwell–Boltzmann distribution shown for a sample of a gas, X, at two different temperatures.


Which statement is correct for the higher temperature?

a)

The area under the curve to the left of Ea decreases.

b)

The total area under the curve increases.

c)

The activation energy decreases.

d)

More molecules have the mean energy.

176.

The graph below shows a typical energy distribution for particles of an ideal gas in a sealed container at a fixed temperature.


Which of the following statements is true?

a)

Position A represents the mean energy of a molecule in the container.

b)

Addition of a catalyst moves the position of EA to the right.

c)

The area under the curve to the right of EA represents the number of molecules with enough energy to react.

d)

The position of the peak of the curve at a higher temperature is further away from both axes.

177.

The diagram shown to the left represents the Maxwell-Boltzmann distribution of an uncatalysed reaction.

The effect of adding a catalyst could be:

1. the curve flattens to reflect the lower activation energy barrier

2. the curve shifts to the right

3. the Ea shifts to the left.

Which of the statements above are correct?

a)

1 only

b)

1 and 2

c)

2 and 3

d)

3 only

178.

An energy profile for a particular uncatalysed reaction is shown to the left.

If a catalyst was used in the reaction, which values would change?

a)

W, X and Z only

b)

W, Y and Z only

c)

W and Z only

d)

X and Y only

179.

Use the following information and the picture to the left to answer Questions 6 and 7.

Cu(s) + 4HNO3(aq) \rightarrow   Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l)

Which one of the following will not increase the rate of the above reaction?

a)

decreasing the size of the solid copper particles

b)

increasing the temperature of HNO3 by 20 °C

c)

increasing the concentration of HNO3

d)

allowing NO2 gas to escape

180.

Shown below in Figure 6 are Maxwell-Boltzmann curves for four different reactions, all occurring at the same temperature.

The activation energies of the four reactions are represented by the symbols Ea1, Ea2, Ea3 and Ea4 respectively.

The order of reaction rates from slowest to fastest is

a)

Reaction 1 < Reaction 2 < Reaction 3 < Reaction 4.

b)

Reaction 3 < Reaction 1 < Reaction 4 < Reaction 2.

c)

Reaction 4 < Reaction 2 < Reaction 1 < Reaction 3.

d)

Reaction 3 < Reaction 1 < Reaction 2 < Reaction 4.

181.

The kinetic energy of the particles involved in the reaction can be represented by the diagram shown to the left.

If a catalyst is added:

a)

the whole graph will shift to the right meaning that more molecules will have enough energy to react

b)

the activation energy shifts to the right meaning that more molecules will have enough energy to react

c)

the activation energy shifts to the left meaning that more molecules will have enough energy to react

d)

the activation energy line stays where it is but the height of the graph at the activation energy point will increase meaning that more molecules will have enough energy to react

182.

What is an appropriate label for the dark blue area indicated by A

a)

particles that can react at the lower temperature

b)

particles that can react at the higher temperature

c)

particles that cannot react at the lower temperature

d)

particles that cannot react at the higher temperature

183.

The reason a higher temperature has a faster rate of reaction is because_:

a)

the white area is smaller than the dark blue area

b)

the white area is larger than than the dark blue area

c)

the white area is equal to the dark blue area

d)

T1 is hotter than T2

184.

A good label for the green area would be:

a)

beautiful neon green stripey baby

b)

quantity of particles with a kinetic energy greater than the activation energy prior to the addition of the catalyst

c)

quantity of particles with a kinetic energy greater than the activation energy after to the addition of the catalyst

d)

quantity of particles with a kinetic energy greater than the activation energy prior to the temperature change

185.

The activation energy when the reaction is run with a catalys is

a)

Z - X

b)

Y

c)

X

d)

Z-Y

186.

Which statements are correct?

I. The activation energy of a reaction is not affected by temperature.

II. A catalyst reduces the enthalpy change of a reaction.

III. Catalysts provide alternative reaction pathways.

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

187.

The diagram shows the energy profile for a catalysed and uncatalysed reaction.

Which represents the enthalpy change, ΔH, and the activation energy, Ea, for the catalysed reaction?

a)

ΔH is z, Ea (catalysed reaction) is x + z

b)

ΔH is z, Ea (catalysed reaction) is z + y

c)

ΔH is -z, Ea (catalysed reaction) is x

d)

ΔH is z + x, Ea (catalysed reaction) is x