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Equilibrium & Le Chatelier's Principle

Total questions: 30

Worksheet time: 15mins

Name
Class
Date
1.
At what time (in seconds) is equilibrium established?
a)
0 seconds
b)
1 second
c)
5 seconds
d)
10 seconds
2.
Le Chaltelier's Principle states that if a chemical system at equilibrium is stressed,
a)
the system will adjust to increase the stress
b)
the system will adjust to reduce the stress
c)
the system will not adjust
3.
When writing an endothermic reaction, heat energy is stated as
a)
product
b)
catalyst
c)
reactant
4.
An exothermic reaction is allowed to reach equilibrium. If heat energy is then removed, the equilibrium will shift
a)
toward the middle
b)
toward the reactant side
c)
toward the product side
5.
For the reaction...
SO2(g) + O2(g) <−>  SO3(g)
If the concentration of 
SO2(g)  is increased, the equilibrium of the reaction will ___________.
a)
shift to the left
b)
shift to the right
c)
not shift
6.
For the reaction...
SO2(g) + O2(g) <−>  SO3(g)

If the equilibrium shifts to the right, the concentration of O2(g) will ___________.
a)
increase
b)
decrease
c)
remain the same
7.
For the reaction...
heat  +  N2(g)  +  O2(g)  <−>  2NO(g)
If the heat is removed to the chemical system, the equilibrium will _______.
a)
shift to the left
b)
shift to the right
c)
not shift
8.
For the reaction...
N2 (g) +  3 H2 (g) <−> 2 NH3 (g)

If the pressure in the system is increased, the reaction will __________________.
a)
 shift to the left
b)
shift to the right
c)
not shift
9.
When  ΔH  is negative it represents a(n)
a)
exothermic reaction 
b)
endothermic reaction 
10.
The three factors that affect the equilibrium of a reaction are temperature, pressure and __________. 
a)
energy
b)
concentration 
c)
enthalpy 
d)
ice 
11.
  A(g) + B(aq) <> C(s) 
 ΔHrxn= -453 kJ/mol
If the [B] is decreased then the reaction is will shift to the _______. 
a)
Left
b)
Right
c)
Stays the same 
d)
Up
12.
 A(g) + B(aq) <> C(s)  + D(s) 
ΔHrxn= 240 kJ/mol
If the pressure decreases then the reaction will shift to the _____. 
a)
left
b)
right
c)
stays the same 
d)
Up
13.
At what time does the reaction reach equilibrium?
a)
t1
b)
t2
c)
t3
d)
t4
14.
2SO2(g)+O2(g)⇌2SO3(g)
Removing O2(g) will
a)
shift equilibrium right
b)
shift equilibrium left
c)
decrease temperature
d)
have no change
15.
2SO2(g)+O2(g)⇌2SO3(g) is an exothermic reaction.
an in Increase temperature will...
a)
shift equilibrium toward the right
b)
shift equilibrium toward the left
c)
increase pressure
d)
have no change
16.

Which is NOT a way to stress a closed chemical system at equilibrium?

a)

change temperature

b)

add a reactant

c)

take away a chemical in the reaction

d)

add a catalyst

17.

A single sided arrow (→), indicates that a reaction is:

a)

Reversible

b)

Irreversible

c)

Not reactive

18.

A double sided arrow (↔), indicates that a reaction is:

a)

Reversible

b)

Irreversible

c)

Not reactive

19.

When the forward and reverse reactions are occurring at the same rate, the reaction is said to be at:

a)

Chemical equilibrium

b)

Chemical reaction

c)

Chemical constant

d)

Chemical peace

20.

Which is the correct equilibrium constant expression for the following reaction?

Fe2O3(s) + 3H2(g) —> 2 Fe(s) + 3H2O(g)

a)

K = [H2O]3 / [H2]3

b)

K = [Fe2O3] [H2]3 / [Fe]2[H2O]3

c)

K = [Fe]2[H2O]3 / [Fe2O3] [H2]3

d)

K= [Fe] [H2O] / [Fe2O3] [H2]

e)

K = [H2] / [H2O]

21.

The equilibrium constant expression for the reaction 2BrF5(g) —> Br2(g) + 5 F2(g) is

a)

Kc = [Br2] [F2] / [BrF5]

b)

Kc = [BrF5]2 / [Br2][F2]5

c)

Kc = [Br2] [F2]5 / [BrF5]2

d)

Kc = 2[BrF5]2 / ([Br2] × 5[F2]5)

e)

Kc = [Br2] [F2]2 / [BrF5]5

22.

Calculate Kc for the reaction HI(g) —> H2(g) + I2(g) given that the concentrations of each species at equilibrium are as follows: [HI] = 0.85 mol/L, [I2] = 0.60 mol/L, [H2] = 0.27mol/L.

a)

0.19

b)

0.22

c)

4.5

d)

5.25

e)

160

23.

A very high value for K indicates that

a)

reactants are favored.

b)

products are favored.

c)

equilibrium is reached slowly.

d)

equilibrium has been reached

24.

Changes in pressure will only affect substances that are in the ______ state.

a)

solid

b)

gas

c)

liquid

25.

Which of the two graphs reaches equilibrium?

a)

Neither

b)

The left

c)

Both

d)

The right

26.

Which of the following is NOT true at equilibrium?

a)

The concentrations of reactants and products do not change.

b)

The forward and reverse reactions proceed at the same rate.

c)

The concentration of the reactants is equal to the concentration of the products.

d)

The forward and reverse reactions continue to occur.

27.

Select all of the statements that are always correct about dynamic equilibrium

a)

established when the product and reactant concentrations are equal

b)

achieved when the forward and reverse reaction rates are same

c)

established when the concentration of reactants is unchanging

d)

achieved when the concentration ratio of reactants to products becomes stable

e)

achieved when the forward and reverse reactions stop occurring

28.

What states of matter are omitted when writing Keq expressions?

a)

solids and liquids

b)

aqueous solutions and gas

c)

solids, liquids, aqueous solutions and gases

d)

aqueous solutions & liquids

29.

When Keq < 1,

a)

There are more products than reactants when the reaction reached equilibrium.

b)

There are more reactant than products when the reaction reached equilibrium.

c)

The amount of reactants is equal to the amount of products.

30.

How would the equilibrium change for the reaction 2 HgO (s) <--> Hg (l) + O2 (g) if more HgO was ADDED

a)

Right ; toward products

b)

Left ; toward reactants

c)

no change because HgO is a solid