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Unit 10 Equilibrium Practice - Chemistry

Total questions: 71

Worksheet time: 2hrs 34mins

Name
Class
Date
1.
When the rate of the forward reaction is equal to the rate of backward reaction, the system is said to be in
a)
Chemical Equilibrium
b)
Chemical Balance
c)
Stoichiometry
d)
Chemical Reaction
2.

At what time (in seconds) is equilibrium established?

a)

0 seconds

b)

1 second

c)

5 seconds

d)

10 seconds

3.
Why is equilibrium called a dynamic state?
a)
Chemists try to convert as much reactants as possible into products.
b)
The reactions at equilibrium continue to take place once equilibrium is established.
c)
The products of a forward reaction are favored, so equilibrium lies to the right.
d)
All chemical reactions are considered to be reversible under suitable conditions.
4.
What is the Kc expression for this reaction?
   2 NO(g)  +  O2(g) ⇌  2 NO2(g)
a)
K= [NO2]2 / [NO][O2]
b)
K=  [NO][O2] / [NO2]2
c)
K= [NO][O2] [NO2]2
d)
K= [NO2]2 / [NO]2 +  [O2]
5.
An equilibrium constant with a large value, e.g. Kc = 1000, indicates…
a)
A very fast reaction
b)
Mostly products at equilibrium
c)
Mostly reactants at equilibrium
d)
Nothing useful at all
6.

When the following reaction reached equilibrium,

SO2 (g) + NO2 (g) <=> SO3 (g) + NO (g)

it was found to contain:

0.40 M SO3 , and 0.30 M NO,

0.15 M NO2 , and 0.20 M SO2.

Calculate the equilibrium constant for this reaction.

a)

4.0

b)

0.42

c)

0.25

d)

1.0

7.

Which is true for a system at equilibrium?

a)

Forward reaction rate is faster than the reverse and concentrations are equal

b)

Forward and reverse reaction rates are equal and concentrations are constant

c)

Forward and reverse reaction rates are equal and concentrations are equal

d)

Forward reaction rate is faster than the reverse and concentrations are constant

8.

What is the correct equilibrium expression for the following reaction:

2H2O2 (aq) ↔ 2H2O (l) + O2 (g)

a)

[H2O]2[O2] / [H2O2]2

b)

[H2O2]2 / [H2O]2[O2]

c)

[O2] / [H2O2]2

d)

[H2O]2 / [H2O2]2

9.
Which is the reactant - and why?
a)
A, as concentration decreases
b)
B, as concentration decreases
c)
A, as concentration increases
d)
B, as concentration increases
10.

When the system X + 2 Y ↔ Z has reached equilibrium, which of the following is TRUE?

a)
Forward reaction and Backward reaction stop.
b)
Forward reaction has sped up and backward reaction has slowed down.
c)
Forward and backward reactions occur at the same rate.
d)
Forward reaction has slowed down and backward reaction has sped up.
11.
At what time the reaction reached equilibrium?
a)
t1
b)
t2
c)
t3
d)
t4
12.
What are [A] and [B]?
a)
concentration of reactants
b)
concentration of products
c)
energy of reactants
d)
energy of products
13.

What is the equilibrium expression for: Fe3O4(s) + 4H2(g) ↔ 3Fe(s) + 4H2O(g) Kc =

a)
[Fe][H2O]4  / [Fe3O4] [H2]4
b)
[Fe3O4] [H2]/  [Fe][H2O]4
c)
[H2O]4 / [H2]4
d)
[Fe] [H2O] / [Fe3O4] [H2]
14.
Which of the two graphs reaches equilibrium?
a)
The left one.
b)
The right one.
c)
Both of them.
d)
Neither.
15.
Which of the following is NOT true at equilibrium?
a)
The forward and reverse reactions proceed at the same rate.
b)
The concentrations of reactants and products do not change.
c)
The concentration of the reactants is equal to the concentration of the products.
d)
The forward and reverse reactions continue to occur.
16.
If a reaction is reversible and has reached equilibrium, what can be said about the amounts of reactants and products?
a)
some reactant, some product
b)
no reactant, all product
c)
all reactant, no product
17.
If the equilibrium constant is much less than one (K << 1) then
a)
Equilibrium is not established.
b)
Equilibrium lies to the right (products are favored)
c)
Equilibrium lies to the left (reactants are favored)
d)
Neither products or reactants are favored.
18.

2SO2(g)+O2(g) ↔ 2SO3(g)

Removing O2(g) will

a)

shift equilibrium right

b)

shift equilibrium left

c)

increase pressure

d)

have no change

19.

2SO2(g)+O2(g) ↔ 2SO3(g) Increasing volume of container will

a)
shift equilibrium right
b)
shift equilibrium left
c)
slow rate of reaction
d)
have no change
20.

2SO2(g) + O2(g) ↔ 2SO3(g) Decreasing volume of container will

a)
shift equilibrium right
b)
shift equilibrium left
c)
change K
d)
have no change
21.
Changes in pressure will only affect substances that are in the __________ state.
a)
gaseous
b)
liquid
c)
solid
d)
plasma
22.

2SO2(g) + O2(g) ↔ 2SO3(g) Using a catalyst

a)
shift equilibrium right
b)
shift equilibrium left
c)
increase rate of reaction
d)
have no change
23.

2SO2(g) + O2(g) ↔ 2SO3(g) + Heat

Increasing the temperature will...

a)

shift equilibrium right

b)

shift equilibrium left

c)

increase pressure

d)

have no change

24.

CoCI42- +6H2O ↔ Co(H2O)62+ + 4CI-.

What would happen when H2O is added?

a)

Position of equilibrium will shift to left (and become more blue)

b)

Position of equilibrium will shift to right (and become more pink)

c)

Keq will increase as H2O is added

d)

Position of equilibrium will shift to left to reduce the added H2O

25.

N2(g) + 3H2(g) ↔ 2NH3(g)

When the pressure on the system is increased, the equilibrium position shifts to the right. Why?

a)

To increase the amount of products

b)

To reduce the pressure, as the right side has fewer molecules of gas

c)

Keq will increase when it is shifted to the right

d)

To increase the pressure, as the right side has more molecules of gas

26.

CoCI42- +6H2O ↔ Co(H2O)62+ + 4CI-

What will happen when CI- ions are added?

a)

Position of equilibrium will shift to left and become more pink

b)

Color of system will turn to all pink

c)

Concentration of reactants and products remain unchanged

d)

Position of equilibrium will shift to left to reduce the added CI- ions

27.

2CrO42- + 2H+ ↔ Cr2O72- + H2O

What will happen when H+ ions are added to the system?

a)

Position of equilibrium will shift to left and become more yellow

b)

Color of system will turn all yellow

c)

Color of system will turn all orange

d)

Equilibrium will shift to right and become more orange

28.

Heat + 1 N2O4 ↔ 2 NO2

What will happen when the temperature is increased?

a)

Position of equilibrium will shift to left and become lighter in color

b)

Position of equilibrium will shift to right and become more brown

c)

No change in position of equilibrium

d)

Position of equilibrium will shift to right and become lighter in color

29.

CoCI42- +6H2O ↔ Co(H2O)62+ + 4CI- + Heat

What will happen when the temperature is increased?

a)

Position of equilibrium will shift to left and become more blue

b)

Position of equilibrium will shift to right and become more pink

c)

No change in position of equilibrium

d)

Position of equilibrium will shift to left and become more pink

30.
When the chemical reaction A + B ↔ C+ D is at equilibrium,
a)
both the forward and reverse reactions have stopped.
b)
the sum of the concentrations of A and B equals the sum of the concentrations of C and D.
c)
all four concentrations are equal.
d)
neither the forward nor the reverse reactions have stopped.
31.
The rate of a chemical reaction is NOT affected by which of the following:
a)
temperature
b)
concentration
c)
particle size (surface area)
d)
All of these affect reaction rates
32.
Products will form faster if____________
a)
the particle size of the reactants are larger.
b)
temperature is decreased.
c)
concentration of the reactants are increased.
d)
the reaction is not stirred.
33.
A ______________ is a substance that increases the rate of a reaction without being used up during the reaction. 
a)
catalyst
b)

inhibitor

c)
reactant
d)
solute
34.

Smaller particle size allows for a _________ surface area to be exposed for the reaction.

a)

larger

b)

smaller

c)

rectangular

d)

spherical

35.

Increasing the ____ causes the particles (atoms

or molecules) of the reactants to move more quickly so that

they collide with each other more frequently and with more

energy.

a)

Catalyst

b)

Surface Area

c)

Temperature

d)

Concentration

36.

________ is the measure of how much area of an

object is exposed.

a)

Surface Area

b)

Catalyst

c)

Temperature

d)

Concentration

37.

Grains of sugar have a greater _______ than a solid cube of

sugar of the same mass, and therefore will dissolve quicker in water.

a)

Surface Area

b)

Catalyst

c)

Temperature

d)

Concentratrion

38.

Pick the TWO (2) options that will INCREASE the rate of a reaction.

a)

Reducing Heat

b)

Adding Catalyst

c)

Adding Heat

d)

Removing Catalyst

39.

Which of the following will lower the rate

of reaction?

a)

adding an enzyme to the reaction

b)

decreasing the temperature from 40°C to

10°C

c)

breaking a chunk of calcium up into

smaller pieces

d)

increasing the amount of solute

dissolved in a solution

40.

Which factors affect the rate of a reaction? (select all that apply)

a)

temperature

b)

concentration

c)

size

d)

pressure

e)

catalyst

41.

Increase in temperature causes the particles to

a)

slow down

b)

move faster

c)

stay apart from each other

d)

move in the correct order

42.

Why does a higher concentration increase the rate of reaction?

a)

it increases the amount of reactants

b)

it lowers the activation energy

c)

it increases the energy of reactant particles

d)

it increases the frequency of collision

43.

Why does a higher temperature increase the rate of a reaction?

a)

It increases both the frequency collision and energy of reactant particles

b)

It only increases the frequency of collision

c)

It only increases the energy of reactant particles

d)

It reduces the activation energy of the reaction

44.
What is the rate of reaction?
a)
How fast a reaction is 
b)
How big a reaction is
c)
How loud a reaction is
d)
How much gas a reaction produces
45.

Grinding an effervescent tablet into powder increases the rate of reaction due to increase of

a)

concentration

b)

total surface area

c)

temperature

d)

size

46.

Increasing pressure causes the reacting particles

a)

to bond together

b)

to repel from each other

c)

gain more kinetic energy

d)

to move closer together

47.

Increasing the temperature gives particles more __________.

a)

time

b)

energy

c)

space

d)

frequency

48.

You add more bodies into a "mosh pit" to hope for more collisions. You have increased

a)

temperature

b)

concentration

c)

pressure

d)

catalyst

49.

You make a space much smaller by increasing the ________________ hoping to increase the reaction rates.

a)

temperature

b)

concentration

c)

catalyst

d)

pressure

50.

What is the name given to a catalyst in the human body?

a)

Inhibitor

b)

Catalyst

c)

Chemical

d)

Enzyme

51.

_______ refers to how much solute is dissolved in

a solution.

a)

Surface Area

b)

Catalyst

c)

Temperature

d)

Concentration

52.

What is the value of the Keq of the reaction: CO(g) + 2H2(g) ↔ CH3OH(g) if the equilibrium concentrations of the reactants and product are: CO=0.17M, H2=0.34M, and CH3OH= 0.17M?

a)

0.085

b)

8.7

c)

0.12

d)

2.9

53.

If K of a reaction is larger than one, the ___ reaction was favored, if K is smaller than one, the ___ reaction was favored.

a)

forward, reverse

b)

reverse, forward

c)

neither reaction was favored in either reaction at equilibrium

54.

Consider the following equation  H2 (g) + I2 (g) ↔ 2 HI(g)   Calculate Keq if at equilibrium the concentrations are [H2] = 0.40 M ,  [I2] = 0.45 M , [HI] = 0.30 M

a)
0.42
b)
0.5
c)
1.67
d)
0.6
55.

The following equilibrium was established in a container at 393 K.

heat + M2(g) + R(g) ⇌ RM2(g)

Which change would increase the yield of RM2? (select all the apply)

a)

Remove some R(g) from reaction vessel

b)

change the temperature to 293 K

c)

remove RM2 as it is formed

d)

Continually add more M2(g) + R(g)

e)

Increase the temperature to 493 K

56.

2SO2(g) + O2(g) ⇌ 2SO3(g) is an exothermic reaction. An increase temperature will...

a)
shift equilibrium toward the right
b)
shift equilibrium toward the left
c)
increase pressure
d)
have no change
57.
The idea that when a system at equilibrium is stressed, it will react to relieve that stress and return to equilibrium is known as:
a)
Boyle's Law
b)
Le Chatelier's Principle
c)
Charles Law
d)

Avagadro's Law

58.
For the reaction...
heat  +  N2  +  O2  <−>  2NO
If  O2 is removed, the  concentration of N2 will _______.
a)
increase
b)
decrease
c)
remain the same
d)
double
59.
For the reaction...
heat  +  N2  +  O2  <−>  2NO
If the heat is removed from the chemical system, the concentration of N2 will _______.
a)
increase
b)
decrease
c)
remain the same
d)
double
60.

Given: 2A(g) <-> 2B(g) + C(g).

Raising the pressure by lowering the volume of the container will...

a)

cause [A] to increase

b)

cause [B] to increase

c)

have no effect

d)

cannot be determined

61.
2A + 3B  <---->  2AB
The forward reaction forms the substance __________.
a)
A
b)
B
c)
AB
d)
A + B
62.
Identify the labels (a) and (b) on the graph.
a)
a is concentration of reactants and b is the concentration of product
b)
a is concentration of product and b is the concentration of reactant
c)
a is the volume of reactants and b is the volume of product
d)
a the mass of reactants and b is the mass of product
63.

If the equilibrium constant is less than 1, it means that

a)

Products are favored

b)

Reactants are favored

64.

The value of Keq tells us...

a)

if the formation of reactant or product is favored

b)

how fast a reaction will occur

c)

how much of each reactant should be added

d)

if the reaction is exothermic or endothermic

65.

What are [C] and [D]?

a)

concentration of reactants

b)

concentration of products

c)

energy of reactants

d)

energy of products

66.
Equilibrium is a __________ process
a)
Static
b)
Dynamic
c)
Probabilistic
d)
Fictitious
67.
At equilibrium the concentration of all species in the reaction is _________.
a)
Constant
b)
Increasing
c)
Decreasing
d)
Oscillating
68.
Increasing the temperature on a ________ reaction will increase the concentration of products.
a)
Endothermic
b)
Exothermic
c)
Isothermic
69.
Decreasing the temperature of an exothermic reaction will shift the reaction to the ________ 
a)
left
b)
right
70.
Adding an inhibitor to a reaction will...
a)
increase the rate of reaction.
b)
decrease the rate of reaction.
c)
increase the equilibrium concentration of products.
d)
increase the equilibrium concentration of reactants.
71.

Which of the following systems would NOT be shifted by a change in the volume of the system at constant temperature?

a)

CO (g) + NO (g) ↔ CO2 (g) + ½N2 (g)

b)

N2 (g) + 3H2 (g) ↔ 2NH3 (g)

c)

N2 (g) + 2O2 (g) ↔ 2 NO2 (g)

d)

NO(g) + O3 (g) ↔ NO2 (g) + O2 (g)