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AP Chemistry Unit 5

Total questions: 49

Worksheet time: 12hrs 15mins

Name
Class
Date
1.

4 factors that affects reaction rate.

a)

temperature

b)

surface area

c)

catalyst

d)

the nature of reactant

2.

Which of the following are true of reaction rates?


I. The overall rate law is determined by the fastest step of a reaction

II. The presence of a catalyst will increase the number of molecules entering the transition state

III. An increase in temperature will increase the rate of a reaction

IV. Increasing the concentration of reactants will increase the rate at which products yield

a)

II+III+IV

b)

I+IV

c)

II + III

d)

I+II+III

3.

Which of the following plots will show a linear relationship for a second order reaction?

a)

[A] vs time

b)

1/[A] vs time

c)

ln[A] vs time

d)

[A]2 vs time

4.

The iodide ion reacts with hypochlorite ion in the following way:

OCl- + I- ⟶ OI- + Cl-.

This rapid reaction gives the rate data shown. What is the rate law?

a)

rate = [OCl-]2[I-]

b)

rate = [OCl-][I-]2

c)

rate = [OCl-][I-]

d)

rate = [OCl-]

5.

A reaction is found to be second order with respect to carbon monoxide. If the concentration of carbon monoxide is doubled, the rate of reaction __________.

a)

doubles

b)

remains unchanged

c)

increases by a factor of 4

d)

is reduced by a factor of 2

6.

What letter represents the activation energy?

a)

A

b)

B

c)

C

d)

D

7.

Which of the two graphs show a state of equilibrium being reached?

a)

A

b)

B

c)

A and B

d)

Neither.

8.

Which of the following best describes why increasing temperature increase reaction rate?

a)

Activation energy is reduced.

b)

Collisions become more frequent.

c)

Collisions become more energetic.

d)

Collisions become more frequent and more energetic.

9.

Which species is the catalyst in this reaction mechanism?

a)

R

b)

W

c)

X

d)

There is no catalyst.

10.

What is the rate law for this mechanism?

a)

rate = k[A][B]2

b)

rate = [B][X]

c)

rate = [A]0.5[B]1.5

d)

rate = [W][Y][Z]

11.
A ______________ is a substance that increases the rate of a reaction without being used up during the reaction. 
a)
catalyst
b)
product
c)
reactant
d)
solute
12.
Why do most reactions begin with a fast rate and then get slower and slower?
a)
they run out of energy
b)
the catalyst runs out
c)
the concentration of reactants decreases
d)
the temperature decreases
13.
Which of the following changes that can be made to a chemical reaction will result in a greater proportion of successful collisions between reactant particles?
I. addition of a catalyst
II. grinding reactant lumps into a powder
III. increasing the concentration of reactants
a)
I only
b)
II and III only
c)
I and II only
d)
I, II and III
14.
Consider the provided energy profile for a particular reaction.
Which of the following is an incorrect conclusion from the data presented?
a)
It takes more energy to break the bonds in the reactants than the energy released when the products form.
b)
The activation energy of the reverse reaction is x+y
c)
The magnitude of the heat of reaction is equal to z-x
d)
When the products form, after bonds in the reactants are broken, energy equivalent to x+y-z is released.
15.
Not all collisions between reactant particles result in the formation of products. This could be due to
i. the molecules not colliding with sufficient energy
ii. the concentration of reactants being low
iii. the reaction reaching equilibrium
iv. the reactants not colliding in the correct orientation
a)
all of the above
b)
i only
c)
iii only
d)
i and iv
16.

The rate expression for the reaction X (g) + 2Y (g) → 3Z (g) is

rate = k[X]0 [Y]2

By which factor will the rate of reaction increase when the concentrations of X and Y are both increased by a factor of 3?

a)

6

b)

9

c)

18

d)

27

17.

Consider the following reaction between nitrogen monoxide and oxygen. 2NO(g)+O2(g)→2NO2(g) The reaction occurs in two steps:

Step 1: NO(g) + NO(g) ⇌ N2O2(g) fast

Step 2: N2O2(g) + O2(g) → 2NO2(g) slow

What is the rate expression for this reaction?

a)

Rate =k[NO]2

b)

Rate =k[NO][O2]

c)

Rate =k[NO]2[O2]

d)

Rate =k[NO][O2]2

18.

Which graph best represents a second-order reaction?

a)

A

b)

B

c)

C

d)

D

19.
The following is true for reaction mechanism EXCEPT
a)
Elementary steps must add up to overall balanced equation
b)
Molecularity for slow and fast step is 2
c)
Proposed mechanism is likely
d)
slow step and fast step dont add up to overall balanced eqn
20.
The following is true on intermediates and transition states EXCEPT
a)
Intermediates exist for a while
b)
Transition state occurs at peak of the curve
c)
Intermediates formed in one step and consumed in the next
d)
Transition state can exist in the reaction mechanism
21.
Which one of the following is a first order, overall reaction
a)
k1= 1.000 M s-1
b)
k1= 5403.2 M½ s½
c)
k1= 1.23 x 10-6 M-1 s-1
d)
k1= 10.7 s-1
22.
a)
A. is most exothermic
b)
B. is most exothermic
c)
C. is most exothermic
d)
D. is most exothermic
23.
Consider the following rate law: Rate = k[A]n[B]m
How are the exponents n and m determined?
a)
by using balanced chemical equation
b)
By using the subscripts for the formulas
c)
By educated guess
d)
By experiment 
24.
a)
A. has largest Ea
b)
B. has largest Ea
c)
C. has largest Ea
d)
E. has largest Ea
25.
a)
A. is the slowest reaction
b)
B. is the slowest reaction
c)
C. is the slowest reaction
d)
E. is the slowest reaction
26.
step 1: O3 → O2 + O
step 2: O3 + O → 2 O2

The oxygen atom (O) is considered to be a(n)...
a)
reactant
b)
catalyst
c)
reaction intermediate
d)
activated complex
27.
The reaction of (CH3)3CBr with hydroxide ion proceeds:
(CH3)3CBr(aq) + OH-(aq) → (CH3)3COH(aq) + Br-(aq)
What will the initial rate (in mol/L*s) be in Experiment 4?
a)
0.003
b)
0.006
c)
0.009
d)
0.018
28.
In any first order reaction, as the reaction proceeds at constant temperature, which describes the corresponding effects on k (the rate constant) and rate?
a)
k remains the same; rate decreases
b)
k and rate both remain the same
c)
k remains the same; rate increases
d)
k decreases; rate remains the same
29.
A compound has a half-life of 14 min. How much time will it take a 12 mol sample to decay to 1.5 mol?
a)
14 min
b)
28 min
c)
42 min
d)
56 min
30.
a)
IO-, because it was used as a reactant in an earlier step and reproduced in a subsequent step
b)
I-, because it was used as a reactant in an earlier step and reproduced in a subsequent step
c)
IO-, because it was produced in an earlier step and used up in a subsequent step
d)
I-, because it was produced in an earlier step and used up in a subsequent step
31.
a)

rate = k[CO]2[O2]2

b)

rate = k[CO]2[O2]

c)

rate = k[CO][O2]2

d)

rate = k[CO][O2]1/2

32.
A catalyst:
a)
should be eliminated when we solve elementary reaction steps of a proposed reaction mechanism simultaneously
b)
should always be introduced and eliminated in the first elementary step of a proposed reaction mechanism
c)
lowers the amount of energy released by an exothermic reaction
d)
lowers the amount of energy added to a reaction 
33.
Increasing temperature of a chemical reaction:
a)
increases the number of collisions per second of chemical reactants
b)
increases the speed of reaction
c)
can increase the pressure of reactants
d)
all of the above
34.
Multi-step (Consecutive) Reactions:
Mechanisms in which one elementary step is followed by another are very common.
step 1:              A + B → Q
step 2:              B + Q → C
net reaction:    A + 2B → C
Which of the following is false?
a)
The net reaction is just the sum of its elementary steps.
b)
The species Q is an intermediate, usually an unstable or highly reactive species. 
c)
Intermediates such as Q can appear in the rate law of a net reaction.
d)
If both steps proceed at similar rates, rate law experiments on the net reaction would not reveal that two separate steps are involved here.The rate law for the reaction would berate=k[A][B]2
35.
The rate law for a reaction is rate = k [A][B]2 Which one of the following statements is false? 
a)
A) If [B] is doubled, the reaction rate will increase by a factor of 4. 
b)
B) The reaction is second order in B.
c)
C) The reaction is first order in A.
d)
D) The reaction is second order overall.
36.

The graph shown depicts the relationship between concentration and time. What is the slope of this line?

a)

-k

b)

-1/k

c)

k

d)

ln[A]o

37.

What is the rate law for this reaction?

a)

rate = k[X]0

b)

rate = k[X]

c)

rate = k[X]2

d)

rate = -k[X]2

38.
What two factors govern whether a collision between reacting particles will be effective?
a)
orientation and potential energy 
b)
kinetic energy and temperature 
c)
kinetic energy and orientation 
d)
potential energy and kinetic energy 
39.
More collisions correspond to a: 
a)
Faster reaction rate  
b)
Slower reaction rate
c)
Constant reaction rate 
d)
None of the above
40.
Which of the following is NOT a factor affecting reaction rate?
a)
temperature
b)
catalysts
c)
particle size
d)
polarity
41.

Decreasing the particle size increases the reaction rate because

a)

It makes particles move faster

b)

It increases the likelihood of collisions with the correct geometry

c)

It decreases the surface area available to react

d)

more surface area allows an increase in the number of collisions

42.
What would be my the overall order of this rate law? 
Rate=[A]2[B]1
a)
0 Order
b)
1st Order
c)
2nd Order
d)
3rd Order
43.
For 2A + B → 2C, the rate of production of C has been found to be 12 M/s. During that reaction, the rate of reaction was?
a)
12 M/s
b)
24 M/s
c)
6 M/s
d)
Cannot tell without more data
44.
For an overall reaction order of 1, what will rate constant "k" have for its units?
a)
1/s          or      s -1
b)
M/s         or      M x s-1
c)
1/Mxs      or    M-1 x s-1
d)
1/M2 x s  or    M-2 x s-1
45.
For an overall reaction order of 2, what will rate constant "k" have for its units?
a)
1/s          or      s-1
b)
M/s         or      M x s-1
c)
1/Mxs      or    M-1 x s-1
d)
1/M2 x s  or    M-2 x s-1
46.
A reaction's rate:
a)
starts faster then slows down
b)
stays constant
c)
starts slower then speeds up
d)
none of the above
47.
Bimolecular means:
a)
2 molecules react
b)
3 molecules react
c)
1 molecule reacts
d)
none of the above
48.
Suppose the reaction: A + 2B AB2 occurs by the following mechanism:
Step 1:  A + B--> AB     slow
Step 2:  AB + B -->ABfast
Overall: A + 2B AB2
The rate law expression must be Rate =______.
a)
(a) k[A]
b)
(b) k[B]
c)
(c) k[A][B]
d)
(d) k[B]2
49.
Consider the following mechanism.
Step 1:     O3        → O2 + O (fast)
Step 2:     O3 + O → 2 O2 (slow)
What is the overall balanced equation?
a)
4 O3 → 3 O2
b)
  O3 → 3 O2
c)
3 O3 → 2 O2
d)
2 O3 → 3 O2