CHEM 131 - ADVANCED GENERAL CHEMISTRY I Le Chatelier's Principle Question Bank Set 5

CHEM 131 - ADVANCED GENERAL

CHEMISTRY I - Le Chatelier’s

Principle

Question Bank - Set 5

Liberty University

Question 1

Question

Consider the following reaction at equilibrium:

2SO2(g)+O2(g)⇌2SO3(g)

If the concentration of SO2is increased, predict the direction in which the

equilibrium will shift according to Le Chatelier’s Principle. Justify your answer.

Solution

Step 1: According to Le Chatelier’s Principle, if the concentration of a reactant

is increased, the system will shift to the right to consume some of the excess

reactant.

Step 2: In this case, increasing the concentration of SO2will cause the

reaction to shift to the right in order to consume some of the additional SO2.

Step 3: By shifting to the right, more SO3will be produced, ultimately

increasing the concentration of SO3to re-establish a new equilibrium.

Step 4: Therefore, the system will shift to the right towards the products

side (increasing SO3concentration) when the concentration of SO2is increased.

Question 2

Question

Consider the following reaction at equilibrium:

N2(g) + 3H2(g)⇌2NH3(g)

If the concentration of nitrogen gas is increased, explain how Le Chatelier’s

Principle can be used to predict the direction of the shift in equilibrium.

Solution

Step 1: According to Le Chatelier’s Principle, if the concentration of any re-

actant or product is changed, the system will shift in a direction that tends to

counteract that change and restore equilibrium.

Step 2: In this reaction, if the concentration of nitrogen gas is increased, the

system will try to counteract this change by shifting the equilibrium position

towards the products side. This means that more ammonia gas will be produced.

Step 3: The shift to the right (products side) occurs because the reaction

consumes nitrogen gas in order to produce ammonia. By shifting the equilib-

rium in this direction, the reaction can help alleviate the increase in nitrogen

concentration and restore equilibrium.

Step 4: Therefore, by applying Le Chatelier’s Principle, we predict that if

the concentration of nitrogen gas is increased, the reaction will shift to produce

more ammonia gas until a new equilibrium is established.

Question 3

Question

Consider the following reaction at equilibrium:

N2O4(g)⇌2NO2(g)

If the concentration of N2O4is doubled at constant temperature, explain

how Le Chatelier’s Principle predicts the shift in equilibrium and the resulting

effect on the equilibrium constant Kc.

Solution

Step 1: According to Le Chatelier’s Principle, when the concentration of one of

the reactants or products is changed, the system will adjust in such a way as to

counteract the change and re-establish a new equilibrium.

Step 2: Doubling the concentration of N2O4will shift the equilibrium to the

left to consume some of the excess N2O4.

Step 3: As a result of the shift to the left, the concentration of N2O4will

decrease, while the concentrations of NO2will increase.

Step 4: The equilibrium constant Kcwill not change with the change in

concentrations. Kcis a constant at a given temperature and changing the

concentrations of reactants or products does not change Kc.

Step 5: In summary, the equilibrium will shift to the left to use up the

excess N2O4, resulting in a decrease in its concentration and an increase in the

concentration of NO2. The equilibrium constant Kcwill remain the same.

Question 4

Question

Consider the equilibrium reaction:

2SO2(g) + O2(g)⇌2SO3(g) ∆H=−198 kJ

If the pressure on the system is increased, predict the direction in which the

equilibrium will shift and justify your answer.

Solution

Step 1: First, let’s analyze the effect of increasing pressure on the system.

According to Le Chatelier’s Principle, when the pressure is increased, the equi-

librium will shift towards the side of the reaction with fewer moles of gas to

counteract the increase in pressure.

Step 2: Let’s examine the number of moles of gas on each side of the reaction.

On the reactant side, we have 3 moles of gas (2SO2and O2). On the product

side, we have 2 moles of gas (2SO3).

Step 3: Since the product side has fewer moles of gas than the reactant side,

increasing the pressure will cause the equilibrium to shift towards the product

side to reduce the pressure on the system.

Step 4: Therefore, in response to an increase in pressure, the equilibrium

will shift to the right, favoring the formation of SO3.

Question 5

Question

Consider the reaction:

N2O4(g)⇌2NO2(g)

If the concentration of N2O4is doubled at constant temperature and pres-

sure, predict the direction in which the equilibrium will shift. Justify your

answer using Le Chatelier’s Principle.

Solution

To determine the direction in which the equilibrium will shift, we need to analyze

the effect of doubling the concentration of N2O4on the equilibrium system.

Step 1: Write the expression for the equilibrium constant. The

equilibrium constant expression for the reaction is given by:

Kc=[NO2]2

[N2O4]

Step 2: Analyze the effect of doubling the concentration of N2O4.

By doubling the concentration of N2O4, the initial concentration would become

2[N2O4]. Therefore, the reaction quotient would change to:

Qc=[NO2]2

2[N2O4]

Step 3: Apply Le Chatelier’s Principle. Since the reaction quotient

Qcis now greater than the equilibrium constant Kc, the reaction will shift to

the right to counteract the increase in N2O4concentration. This means that

the concentration of N2O4will decrease while the concentrations of NO2will

increase until a new equilibrium is established.

Therefore, the equilibrium will shift to the right when the concentration of

N2O4is doubled.

Question 6

Question

Consider the following equilibrium:

N2(g) + 3H2(g)⇌2NH3(g)

If the temperature of the system is increased, predict the direction in which

the equilibrium will shift and explain why.

Solution

Step 1: Le Chatelier’s Principle states that a system at equilibrium will respond

to a stress by shifting the equilibrium position in a direction that helps to relieve

the stress.

Step 2: Increasing the temperature of a reaction system is a stress because

heat is considered a reactant or a product in most reactions.

Step 3: In this case, the reaction is exothermic, because the forward reac-

tion releases heat. Therefore, adding heat to the system will favor the reverse

reaction (endothermic) to absorb the excess heat.

Step 4: The equilibrium will shift to the left to consume some of the added

heat, producing more N2 and H2 at the expense of NH3.

Step 5: Thus, when the temperature is increased, the equilibrium will shift

in the direction of the reactants to relieve the stress, resulting in an increase in

the concentration of N2 and H2, and a decrease in the concentration of NH3.

Question 7

Question

Consider the following equilibrium reaction:

2A(g) + B(g) ⇌3C(g)

If the concentration of substance A is increased, predict the effect on the

equilibrium position according to Le Chatelier’s Principle. Justify your answer

with a detailed explanation.

Solution

Step 1: Recall Le Chatelier’s Principle, which states that if a system at equi-

librium is subjected to a change in temperature, pressure, or concentration of

reactants/products, the system will shift its position of equilibrium to counter-

act the change and establish a new equilibrium state.

Step 2: In this case, if the concentration of substance A is increased, the

system will react to counteract this change and establish a new equilibrium

position.

Step 3: When the concentration of A is increased, according to Le Chate-

lier’s Principle, the equilibrium will shift to the right to consume some of the

additional A until a new equilibrium is reached.

Step 4: By shifting to the right, more B will be consumed to produce more

C until a new equilibrium is established.

Step 5: Consequently, the concentration of C will increase, while the con-

centrations of A and B will decrease.

Step 6: Therefore, increasing the concentration of substance A will lead to

an increase in the concentration of substance C and a decrease in the concen-

trations of substances A and B at the new equilibrium position.

Question 8

Question

Consider the exothermic reaction:

2A(g) + B(g) ⇌2C(g)

If the equilibrium constant Kcfor the reaction is 3.5 at a certain temperature,

and the equilibrium concentrations are [A] = 0.10 M, [B] = 0.20 M, and [C] =

0.30 M, how will the equilibrium shift if the volume of the container is decreased

at constant temperature?

Solution

Step 1: Write the expression for Kc:

Kc=[C]2

[A]2

·[B] = 3.5

Step 2: Calculate the initial reaction quotient Qc:

Qc=(0.30)2

(0.10)2·(0.20) = 4.5

Step 3: Compare Qcto Kcto determine the initial direction of the reaction:

- Since Qc> Kc, the reaction will shift to the left to reach equilibrium.

Step 4: If the volume of the container is decreased, the system will try

to counteract the change by favoring the reaction which produces fewer gas

molecules. In this case, the left side of the reaction has fewer gas molecules

than the right side.

Step 5: The shift to the left will continue until a new equilibrium is es-

tablished. The concentrations of A, B, and C will adjust accordingly, but the

equilibrium constant will remain the same.

Question 9

Question

Consider the following reaction at equilibrium:

N2O4(g)⇌2NO2(g)

If the pressure on the system is increased by decreasing the volume, predict

the direction of the shift according to Le Chatelier’s Principle. Justify your

answer.

Solution

1. According to Le Chatelier’s Principle, when a system at equilibrium is

disturbed by a change in temperature, pressure, or concentration, the

equilibrium position will shift to counteract the imposed change.

2. In this case, by decreasing the volume of the system (which increases the

pressure), the system tries to counteract this increase in pressure.

3. The system will shift in the direction that reduces the total number of gas

molecules, as this will help decrease the pressure.

4. In the given reaction, 1 mole of N2O4decomposes to form 2 moles of

NO2. Therefore, as the equilibrium shifts to the right (products), it will

consume more N2O4to decrease the total number of gas molecules.

5. Thus, the equilibrium will shift to the right to produce more NO2and

reduce the pressure caused by the decreased volume.

Question 10

Question

Consider the following reaction at equilibrium:

2 NOCl(g) ⇌2 NO(g) + Cl2(g)

If the pressure of the system is increased by decreasing the volume, pre-

dict the direction in which the equilibrium will shift and explain why using Le

Chatelier’s Principle.

Solution

Step 1: Identify the changes introduced to the system: The pressure of the

system is increased by decreasing the volume.

Step 2: Predict the direction of the equilibrium shift: According to Le

Chatelier’s Principle, when the pressure is increased, the system will shift in

the direction that decreases the total number of gas molecules.

Step 3: Analyze the stoichiometry of the reaction: On the reactant side of

the reaction, there are 3 gas molecules (2 NOCl) and on the product side of the

reaction, there are 3 gas molecules (2 NO + Cl2).

Step 4: Determine the direction of the equilibrium shift: Since both the reac-

tant and product side of the reaction contain the same number of gas molecules,

changing the pressure by decreasing the volume will not favor either the reac-

tants or products. The equilibrium will not shift in either direction in response

to the change in pressure.

Question 11

Question

Consider the following reaction at equilibrium:

2 SO2(g)+O2(g)⇌2SO3(g)

If the temperature of the system is increased, predict the direction in which the

equilibrium will shift according to Le Chatelier’s Principle.

Solution

Step 1: When the temperature of the system is increased, the equilibrium will

shift in the direction that absorbs heat.

Step 2: In this reaction, the forward reaction is exothermic (heat is released)

and the reverse reaction is endothermic (heat is absorbed).

Step 3: Increasing the temperature of the system will favor the reaction that

absorbs heat (endothermic reaction).

Step 4: Therefore, the equilibrium will shift to the right (towards the prod-

ucts) to absorb the excess heat, increasing the concentration of SO3and main-

taining equilibrium.

Question 12

Question

Consider the following reaction at equilibrium:

2 SO2(g) + O2(g) ⇌2SO3(g)

Explain how the equilibrium will shift if the pressure of the system is in-

creased. Justify your answer using Le Chatelier’s Principle.

Solution

To understand how the equilibrium will shift if the pressure of the system is

increased, we need to consider the effect of pressure on the system.

Step 1: When the pressure is increased, according to Le Chatelier’s Princi-

ple, the system will shift in a way that minimizes the change in pressure.

Step 2: In this reaction, there are a total of 3 moles of gas on the reactant

side and 2 moles of gas on the product side. Therefore, increasing the pressure

will cause the system to shift towards the side with fewer moles of gas to reduce

the pressure.

Step 3: Since the reactant side has more moles of gas than the product

side, the equilibrium will shift to the right to decrease the pressure. This means

that more SO3 will be formed from SO2 and O2.

Step 4: Therefore, increasing the pressure will favor the formation of more

SO3 at equilibrium in order to minimize the change in pressure in the system.

Question 13

Question

Consider the reaction:

N2O4(g)⇌2NO2(g)

If the pressure is increased by compressing the system, predict the direc-

tion in which the equilibrium will shift and explain why using Le Chatelier’s

Principle.

Solution

Step 1: When the pressure is increased by compressing the system, according

to Le Chatelier’s Principle, the system will shift in the direction that reduces

the total number of moles of gas molecules.

Step 2: In the given reaction, on the reactant side, there is 1 mole of N2O4

and on the product side, there are 2 moles of NO2. Therefore, decreasing the

number of moles of gas molecules would shift the equilibrium towards the side

with fewer moles to relieve the pressure.

Step 3: Since the products side has more moles of gas molecules, the equi-

librium will shift to the left, favoring the formation of N2O4, to reduce the total

pressure.

Therefore, if the pressure is increased by compressing the system, the equi-

librium will shift to the left, towards the formation of more N2O4.

Question 14

Question

Consider the reaction:

2SO2(g)+O2(g)⇌2SO3(g)

What will happen to the equilibrium position if the volume of the container

is decreased?

Solution

Le Chatelier’s Principle states that if a system at equilibrium is disturbed by

a change in conditions (such as concentration, temperature, or pressure), the

system will shift its equilibrium position to counteract the effect of the distur-

bance.

Step 1: Decreasing the volume of the container will increase the total pres-

sure inside the container.

Step 2: Since there are more moles of gas on the reactant side of the reaction

(2SO2(g)+O2(g)) than on the product side (2SO3(g)), decreasing the volume

will favor the side of the reaction with fewer moles of gas to reduce the pressure.

Step 3: Therefore, the equilibrium will shift to the left, consuming some of

the reactants (SO2and O2) to produce more products (SO3).

Step 4: As a result, the concentrations of SO2and O2will decrease, while

the concentration of SO3will increase to re-establish equilibrium.

Thus, the equilibrium position will shift to the left in response to the decrease

in volume of the container.

Question 15

Question

Consider the following reaction at equilibrium:

2 SO3(g)⇌2SO2(g)+O2(g)

If the pressure of the system is increased by decreasing the volume, predict

the direction of shift of the equilibrium (i.e., left, right, or no shift) according

to Le Chatelier’s Principle. Justify your answer with an explanation.

Solution

Step 1: Identify the effect of decreasing the volume on the system: When the

volume is decreased, the pressure of the system increases.

Step 2: Recall Le Chatelier’s Principle: Le Chatelier’s Principle states that

when a system at equilibrium is disturbed by an external stress (such as a change

in pressure, temperature, or concentration), the system will shift its equilibrium

position to counteract the stress and partially alleviate the disturbance.

Step 3: Determine the direction of shift of the equilibrium: Since the pressure

of the system increases with a decrease in volume, the system will shift in the

direction that helps reduce the pressure. In this case, the reaction will shift to

the side with fewer gas molecules in order to decrease the overall pressure.

Step 4: Analyze the number of gas molecules on each side of the reaction:

On the left side of the reaction, there are 3 gas molecules (2 molecules of SO3),

while on the right side, there are 3 gas molecules (2 molecules of SO2 and 1

molecule of O2).

Step 5: Determine the direction of shift based on the number of gas molecules:

Since the number of gas molecules is the same on both sides of the reaction,

there will be no shift in the equilibrium position when the pressure is increased

by decreasing the volume.

Therefore, according to Le Chatelier’s Principle, there will be no shift in the

equilibrium position of the reaction when the pressure is increased by decreasing

the volume.

Question 16

Question

Consider the following equilibrium reaction:

N2O4(g)⇌2NO2(g)

If the volume of the container is decreased, predict how the equilibrium will

shift according to Le Chatelier’s Principle. Justify your answer.

Solution

1. When the volume of the container is decreased, the pressure inside the

container will increase. According to Le Chatelier’s Principle, the system

will shift in a way that reduces the pressure.

2. Since there are more moles of gas on the right side of the reaction (2

moles of NO2) compared to the left side (1 mole of N2O4), the decrease

in volume will cause the equilibrium to shift towards the side with fewer

moles of gas to reduce the pressure.

3. Therefore, the equilibrium will shift to the left to decrease the number of

gas molecules and alleviate the increase in pressure caused by the decrease

in volume.

Question 17

Question

Consider the following reaction at equilibrium:

2A(g) + B(g)⇌C(g)

If the pressure of the system is increased, predict the direction in which the

equilibrium will shift and explain why using Le Chatelier’s Principle.

Solution

Step-by-step solution to predicting the shift in equilibrium when the pressure

of the system is increased:

Step 1: Increasing the pressure of the system will cause the equilibrium to

shift in the direction that reduces the total number of moles of gas molecules.

This is because when the pressure is increased, the system will try to decrease

the pressure by favoring the reaction that results in fewer gas molecules.

Step 2: In the given reaction, there are 3 moles of gas molecules on the

left-hand side and 1 mole of gas molecule on the right-hand side. Therefore,

increasing the pressure will cause the equilibrium to shift in the direction that

reduces the total number of moles of gas molecules.

Step 3: To reduce the total number of moles of gas molecules, the equilib-

rium will shift to the left (towards the reactants). This means the concentration

of A and B will increase, and the concentration of C will decrease in order to

establish a new equilibrium position.

Thus, when the pressure of the system is increased, the equilibrium will shift

to the left to reduce the total number of moles of gas molecules according to Le

Chatelier’s Principle.

Question 18

Question

Consider the following equilibrium reaction:

2 SO2(g)+O2(g)⇌2 SO3(g)

If the concentration of SO3is increased by adding more of it to the system

at equilibrium, predict the direction in which the equilibrium will shift. Justify

your answer.

Solution

To determine how the equilibrium will shift when the concentration of SO3is

increased, we need to analyze the reaction in terms of Le Chatelier’s Principle.

Step 1: Determine the Effect of Increasing SO3Concentration.

Increasing the concentration of SO3will cause the reaction to shift to the left

to counteract this increase because the equilibrium position wants to minimize

the change in SO3concentration.

Step 2: Write the Reaction with the Shift.

After the shift, the new equilibrium reaction will be:

2 SO2(g)+O2(g)⇌2 SO3(g)+Q

where Q represents the other reactant or product that may be affected by

the shift.

Step 3: Justify the Direction of the Shift.

By adding more SO3, the reaction proceeds in the reverse direction to con-

sume some of the excess SO3. Therefore, the equilibrium will shift to the left

(towards the reactants) to decrease the concentration of SO3and re-establish

equilibrium.

Thus, the equilibrium will shift to the left when the concentration of SO3is

increased.

Question 19

Question

Consider the following equilibrium reaction:

2 SO2(g)+O2(g)⇌2 SO3(g)

If the temperature is increased, predict the effect on the equilibrium position

and justify your answer.

Solution

Step 1: Le Chatelier’s Principle states that when a system at equilibrium is

subjected to a change in concentration, pressure, temperature, or volume, the

system will adjust to counteract the effect of that change and a new equilibrium

position will be established.

Step 2: For the given reaction, an increase in temperature will shift the

equilibrium position in the endothermic direction to consume the added heat.

Step 3: In the reaction given, the forward reaction is endothermic because

it absorbs heat. This means that increasing the temperature will favor the

endothermic reaction (the forward reaction) in order to consume the additional

heat.

Step 4: As a result, the equilibrium position will shift to the right, favor-

ing the formation of more SO3gas molecules at the expense of SO2and O2

molecules.

Step 5: Therefore, increasing the temperature will shift the equilibrium po-

sition towards the formation of more SO3molecules.

Step 6: In summary, increasing the temperature will favor the forward reac-

tion, resulting in an increase in the concentration of SO3and a decrease in the

concentrations of SO2and O2at equilibrium.

Question 20

Question

Consider the following reaction at equilibrium:

N2(g) + 3H2(g)⇌2NH3(g)

If the pressure is increased by reducing the volume of the container, predict

the effect on the equilibrium position. Justify your answer.

Solution

To predict the effect on the equilibrium position when the pressure is increased

by reducing the volume of the container, we need to analyze Le Chatelier’s

Principle.

Step 1: When the pressure is increased by reducing the volume of the

container, the system will respond by trying to decrease the pressure. This can

be done by favoring the reaction that produces fewer gas molecules.

Step 2: In the given reaction, there are 4 moles of gas on the reactant side

(N2and 3H2) and 2 moles of gas on the product side (2NH3).

Step 3: To reduce the pressure, the system will shift towards the side with

fewer moles of gas. Therefore, the equilibrium position will shift to the left to

decrease the pressure by lowering the total number of gas molecules.

Step 4: In conclusion, when the pressure is increased by reducing the volume

of the container, the equilibrium position will shift to the left, favoring the

reactants N2and H2.

Question 21

Question

Consider the following equilibrium reaction:

2A(g) + B(g) ⇌C(g)

If the concentration of A is increased while keeping the total pressure con-

stant, predict the effect on the concentration of B and C. Justify your answer

using Le Chatelier’s Principle.

Solution

Step 1: When the concentration of A is increased, the reaction will shift to the

right to alleviate the stress. This is because an increase in the concentration

of one of the reactants will favor the forward reaction in order to consume the

excess reactant.

Step 2: As the reaction shifts to the right, the concentration of A will de-

crease as it is consumed.

Step 3: To re-establish equilibrium, the concentration of B will also decrease

as it is being consumed in the forward reaction.

Step 4: Since C is being formed in the forward reaction, its concentration

will increase as the reaction proceeds to the right.

Step 5: Therefore, increasing the concentration of A at constant total pres-

sure will result in a decrease in the concentrations of B and A, while causing an

increase in the concentration of C.

Question 22

Question

Consider the exothermic reaction:

2NO2(g)⇌N2O4(g)

If the temperature of the system is increased, predict the effect on the equi-

librium position. Justify your answer.

Solution

Step 1: Le Chatelier’s principle states that if a system at equilibrium is subjected

to a change in concentration, pressure, volume, or temperature, the equilibrium

will shift in the direction that tends to counteract this change.

Step 2: In an exothermic reaction like the one given, heat is treated as a

product on the reactant side. Increasing the temperature of the system will

therefore shift the equilibrium position in the direction that consumes heat, i.e.,

in the endothermic direction.

Step 3: The endothermic reaction is the reverse reaction of the given reac-

tion. Thus, by increasing the temperature, the equilibrium position will shift

to the left, favoring the formation of more NO2(g) from N2O4(g) in order to

consume the excess heat.

Step 4: Therefore, when the temperature is increased, the equilibrium posi-

tion will shift to the left, favoring the formation of more NO2(g) from N2O4(g).

Question 23

Question

Consider the following reaction at equilibrium:

2SO2(g)+O2(g)⇌2SO3(g) + heat

Predict how the following changes will affect the equilibrium position:

1. Adding more SO2gas

2. Increasing the temperature

Solution

Le Chatelier’s Principle states that if a system at equilibrium is subjected to a

change, the system will react in a way that opposes the change. Let’s consider

the two scenarios:

1. Adding more SO2gas: Adding more reactant (SO2) causes the sys-

tem to shift towards the product side to compensate for the increase in

reactant. This is to consume the excess reactant added. The equilibrium

position will shift to the right to form more SO3until a new equilibrium

is established.

2. Increasing the temperature: The reaction given is exothermic (as heat

is a product). Increasing the temperature will shift the equilibrium posi-

tion to consume the excess heat. According to Le Chatelier’s Principle, the

system will shift in the endothermic direction, which is to the left. This

means that more reactants (SO2and O2) will be formed at the expense

of products (SO3).

Question 24

Question

Consider the following reaction at equilibrium:

H2O(g)⇌H2O(l)

Describe how each of the following changes would affect the position of the

equilibrium (shift to the left, shift to the right, or no change):

1. Increasing the pressure by decreasing the volume of the container at con-

stant temperature.

2. Adding more liquid water to the system.

3. Removing some of the gaseous water molecules from the system.

Solution

Le Chatelier’s Principle states that if a system in equilibrium is subjected to

a change, the system will adjust itself in order to counteract the effect of that

change and restore equilibrium. Let’s analyze each scenario one by one:

1. Increasing the pressure by decreasing the volume of the con-

tainer at constant temperature:

Step 1: In this scenario, by decreasing the volume of the container (in-

creasing the pressure), the system will try to decrease the pressure by

favoring the side of the reaction with fewer gas molecules.

This reaction has one gaseous water molecule on the left side and no

gaseous water molecules on the right side. Therefore, the equilibrium will

shift to the right, favoring the formation of liquid water to decrease the

pressure.

2. Adding more liquid water to the system:

Step 1: When more liquid water is added to the system, it will disrupt

the equilibrium by changing the concentration of water molecules. The

system will react to counteract this change.

Since the system is already in equilibrium, the equilibrium will shift to the

left to consume some of the excess liquid water, favoring the formation of

gaseous water until a new equilibrium is established.

3. Removing some of the gaseous water molecules from the system:

Step 1: If some of the gaseous water molecules are removed from the

system, the system will try to counteract this change by shifting the equi-

librium to restore the lost gaseous water molecules.

The equilibrium will shift to the left, favoring the reverse reaction to

produce more gaseous water molecules until a new equilibrium is reached.

Question 25

Question

Consider the following equilibrium reaction:

2SO2(g)+O2(g)⇌2SO3(g)

If the temperature of the system is increased, predict the effect on the equi-

librium position and justify your answer.

Solution

Step 1: Write out the balanced equation:

2SO2(g)+O2(g)⇌2SO3(g)

Step 2: Determine the effect of increasing the temperature on the equilibrium

position: - In this exothermic reaction, the forward reaction is the exothermic

reaction where heat is released as the reactants form products. According to

Le Chatelier’s Principle, increasing the temperature will favor the endothermic

reverse reaction in order to absorb the added heat. Therefore, the equilibrium

position will shift to the left to consume the excess heat.

Step 3: Justify the prediction: - By increasing the temperature of the system,

the equilibrium position will shift to the left to counteract the increase in tem-

perature. This will result in an increase in the concentrations of the reactants

SO2(g) and O2(g) and a decrease in the concentration of product SO3(g).

Therefore, increasing the temperature of the system will cause the equilib-

rium position to shift to the left.

Question 26

Question

Consider the reaction:

2H2O(g)⇌2H2(g)+O2(g)

at equilibrium. If the pressure is increased by decreasing the volume of the

container, predict the shift in equilibrium and explain your reasoning.

Solution

Step 1: According to Le Chatelier’s Principle, when the pressure is increased

in a system at equilibrium, the system will shift in a direction that reduces the

total pressure.

Step 2: In this reaction, there are 3 moles of gas on the left side and 3 moles

of gas on the right side.

Step 3: If the pressure is increased by decreasing the volume, the system

will shift towards the side with fewer moles of gas to reduce the pressure.

Step 4: Therefore, the equilibrium will shift to the right, favoring the for-

mation of more gas molecules.

Step 5: Consequently, at the new equilibrium, the concentration of H2(g)andO2(g)willincrease, whiletheconcentrationofH2O(g)willdecrease.

Question 27

Question

Consider the reaction:

2SO2(g)+O2(g)⇌2SO3(g)

Predict the direction in which the equilibrium will shift if the pressure is in-

creased by decreasing the volume of the container. Justify your answer.

Solution

Step 1: Determine the effect of increasing pressure on the system. - According

to Le Chatelier’s Principle, if the pressure is increased by decreasing the volume

of the container, the system will shift towards the side with fewer gas molecules

to reduce the pressure.

Step 2: Calculate the total number of gas molecules on each side of the

reaction. - On the reactant side, there are 3 gas molecules (2SO2and O2). - On

the product side, there are 2 gas molecules (2SO3).

Step 3: Compare the number of gas molecules on each side. - Since the side

with fewer gas molecules has the products (2SO3), the equilibrium will shift to

the right towards the products to decrease the pressure.

Step 4: Justify the shift in equilibrium. - By shifting to the right, the system

can reduce the total number of gas molecules in the system, thereby reducing

the pressure caused by the decrease in volume.

Therefore, if the pressure is increased by decreasing the volume of the con-

tainer, the equilibrium will shift to the right (towards the products) to counter-

act the increase in pressure.

Question 28

Question

Consider the following reaction at equilibrium:

2 NOCl(g)⇌2 NO(g) + Cl2(g)

How will each of the following changes affect the equilibrium position of the

system? Justify your answers.

(a) Increasing the volume of the container.

(b) Adding more Cl2tothesystem.

Solution

(a) When the volume of the container is increased, the total pressure of the

system decreases due to the decrease in gas particle density. According to Le

Chatelier’s Principle, the system will shift in the direction that alleviates the

stress imposed on it.

Step 1: Increase in volume

Since there are 3 moles of gas particles on the left side of the reaction and

only 3 moles of gas particles on the right side (2 NO(g) + Cl2(g)), changing the

volume will not favor either side of the reaction.

Therefore, the equilibrium position will not be affected by increasing the

volume of the container.

(b) When more Cl2isaddedtothesystem, theconcentrationof Cl2increases.AccordingtoLeChatelier′sP rinciple, thesystemwillreactinawaytocounteractthisincreaseinordertoreestablishequilibrium.

Step 1: Addition of Cl2

By adding more Cl2, theequilibriumpositionwillshif ttothelef ttoconsumesomeoftheextraCl2.T hisshiftwillresultinanincreaseintheconcentrationsofNOClandadecreaseintheconcentrationsof NOandCl2, eventuallyre−

establishingequilibrium.

Question 29

Question

Consider the reaction:

N2O4(g)⇌2NO2(g)

Explain how the following changes affect the position of equilibrium and the

concentration of products and reactants:

1. Increasing the pressure by decreasing the volume of the container.

2. Adding an inert gas to the system at constant volume.

Solution

To analyze how the changes affect the position of equilibrium and the concen-

tration of products and reactants, we can apply Le Chatelier’s Principle.

For increasing the pressure by decreasing the volume:

1. Step 1: According to Le Chatelier’s Principle, when the pressure is in-

creased, the reaction will shift to the side with fewer gas molecules to

decrease the pressure.

2. Step 2: In this reaction, there are 2 moles of gas on the left (N2O4) and

2 moles of gas on the right (2NO2). As the number of moles of gas is the

same on both sides, there will be no effect on the position of equilibrium

in this case.

3. Step 3: However, when the volume is decreased, the pressure increases,

and the system will try to decrease the pressure by shifting to the side with

fewer gas molecules. Since the number of moles is equal on both sides, the

reaction will not favor the formation of either product or reactant.

For adding an inert gas to the system at constant volume:

1. Step 1: When an inert gas is added to the system at constant volume, it

does not affect the equilibrium position because inert gases do not partic-

ipate in the reaction.

2. Step 2: The total pressure in the system will increase due to the addition

of the inert gas, but this increase in pressure does not affect the position

of equilibrium. The system will not shift to either side to counteract the

change in pressure.

3. Step 3: Therefore, adding an inert gas at constant volume will not af-

fect the concentration of products and reactants and will not shift the

equilibrium position of the reaction.

Question 30

Question

Consider the following reaction at equilibrium:

2 SO2(g)+O2(g)⇌2 SO3(g)

If the volume of the container is suddenly decreased, predict and explain

the direction in which the equilibrium will shift according to Le Chatelier’s

Principle.

Solution

Step 1: When the volume of the container is decreased, the total pressure

inside the container increases.

Step 2: According to Le Chatelier’s Principle, the system will shift in a

direction that helps alleviate the change caused by the decrease in volume.

Step 3: In this reaction, the total number of moles of gas on the left side

of the reaction is 3 (2 moles of SO2 + 1 mole of O2) while on the right side, it

is 2 (2 moles of SO3).

Step 4: Therefore, the system will shift to the side with fewer moles of gas

in order to decrease the pressure inside the container.

Step 5: In this case, the system will shift to the left side of the reaction to

decrease the total pressure inside the container.

Step 6: Therefore, when the volume of the container is suddenly decreased,

the equilibrium will shift to the left to relieve the increase in pressure and

establish a new equilibrium.

Question 31

Question

Consider the equilibrium reaction:

H2O(g)⇌H2O(l)

If the volume of the container is decreased at constant temperature, pre-

dict how the equilibrium will shift. Justify your answer using Le Chatelier’s

Principle.

Solution

Step 1: When the volume of the container is decreased at constant temperature,

the system will try to counteract this change by favoring the reaction that

produces fewer gas molecules. In this case, the liquid phase has fewer gas

molecules compared to the gaseous phase.

Step 2: According to Le Chatelier’s Principle, the system will shift to the

side of the reaction that reduces the pressure.

Step 3: Since the liquid phase has a lower partial pressure than the gaseous

phase, the equilibrium will shift to the right, favoring the formation of liquid

water to decrease the total pressure and counteract the volume decrease.

Therefore, the equilibrium will shift towards the right to form more liquid

water and alleviate the pressure increase caused by the volume decrease.

Question 32

Question

Consider the reaction:

H2(g) + I2(g) ⇌2HI(g)

If the equilibrium constant, Kc, for the reaction is 60 at a certain tempera-

ture, predict the direction in which the equilibrium will shift if:

1. The pressure of the system is increased by decreasing the volume.

2. Some HI gas is added to the system.

Solution

1. If the pressure of the system is increased by decreasing the volume, the

equilibrium will shift to the side with fewer gas molecules to alleviate the increase

in pressure.

Step 1: Determine the change in the number of gas molecules on each side

of the reaction.

On the reactant side: 1 (from H2) + 1 (from I2) = 2 molecules of gas

On the product side: 2 (from HI)

Step 2: Compare the number of gas molecules on each side.

Since there are fewer gas molecules on the product side, the equilibrium will

shift to the right to decrease the pressure caused by decreasing the volume.

2. If some HI gas is added to the system, the equilibrium will shift to

counteract the increase in HI concentration.

Step 1: Write the ICE (Initial, Change, Equilibrium) table assuming x mol

of HI is added.

Species Initial Change Equilibrium

H2−

I2−

HI −+x

Step 2: Use the stoichiometry of the reaction to fill in the changes and

equilibrium concentrations.

Since 2 moles of HI are formed for every mole of H2and I2consumed, the

equilibrium concentrations will be:

[H2] = [I2] = −x

[HI] = x

Step 3: Express the equilibrium constant, Kc, in terms of the equilibrium

concentrations.

Kc =[HI]2

[H2][I2]=(x)2

(−x)(−x)= 60

Step 4: Solve for x.

x=√60

Thus, adding HI gas to the system will shift the equilibrium to the left to

consume the excess HI added.

Question 33

Question

Consider the following equilibrium reaction:

2 CO(g)+O2(g)⇌2 CO2(g)

If the pressure is increased by decreasing the volume of the container, predict

the direction in which the equilibrium will shift according to Le Chatelier’s

Principle. Justify your answer.

Solution

Step 1: When the pressure on a system at equilibrium is increased, the equi-

librium will shift in the direction that reduces the total number of moles of

gas.

Step 2: In this equilibrium, there are 3 moles of gas on the left side of the

reaction (2 moles of CO and 1 mole of O2) and 2 moles of gas on the right side

(2 moles of CO2).

Step 3: By decreasing the volume and increasing the pressure, the system

will favor the direction with fewer moles of gas to relieve the pressure increase.

Step 4: Therefore, the equilibrium will shift to the right to decrease the total

number of moles of gas, resulting in the formation of more CO2.

Step 5: In conclusion, when the pressure is increased by decreasing the

volume of the container, the equilibrium will shift to the right to alleviate the

pressure increase, favoring the formation of more CO2 gas.

Question 34

Question

For the reaction:

N2O4(g)⇌2NO2(g) + heat

If the equilibrium constant, Kc, for the reaction at a certain temperature

is equal to 0.83, how will each of the following changes affect the equilibrium

position of the reaction?

Change 1: Addition of more NO2(g) to the system

Change 2: Increase in temperature

Change 3: Decrease in volume of the container

Solution

To determine how each change will affect the equilibrium position of the reac-

tion, we can analyze the impact on the concentration, pressure, or temperature,

and then apply Le Chatelier’s Principle.

Let’s consider each change one by one.

Change 1: Addition of more NO2(g)to the system

Step 1: Adding more NO2(g) will increase the concentration of NO2(g) in

the system. According to Le Chatelier’s Principle, the system will respond in

a way to counteract this change. In this case, the reaction will shift to the left

to consume some of the excess NO2(g) and produce more N2O4(g) until a new

equilibrium is reached.

Step 2: This will result in an increase in the concentration of N2O4(g) and

a decrease in the concentration of NO2(g) at the new equilibrium position.

Change 2: Increase in temperature

Step 1: Increasing the temperature of an endothermic reaction will favor the

endothermic direction to absorb the excess heat. In this case, by Le Chatelier’s

Principle, the reaction will shift to the right to consume the added heat.

Step 2: As the reaction shifts to the right, more NO2(g) will be formed,

and the concentration of NO2(g) will increase at the new equilibrium position.

Change 3: Decrease in volume of the container

Step 1: A decrease in volume will increase the pressure in the system. The

reaction will shift in a direction that reduces the total number of moles of gas

to counteract this increase in pressure.

Step 2: In this reaction, there is a net decrease of 1 mole of gas on the

right side compared to the left side. Therefore, the reaction will shift to the

right (consume N2O4(g) to produce more NO2(g) to decrease the total number

of moles of gas) to relieve the increase in pressure.

In conclusion, the equilibrium position of the reaction will shift as follows

for each change: 1. Addition of more NO2(g): Shift to the left 2. Increase in

temperature: Shift to the right 3. Decrease in volume of the container: Shift to

the right

Question 35

Question

Consider the following reaction:

2 CO(g) + O2(g)⇌2 CO2(g) + heat

How will the following changes affect the position of equilibrium according to

Le Chatelier’s Principle? (a) Increasing the pressure by decreasing the volume

of the container. (b) Adding an inert gas to the system at constant volume. (c)

Increasing the concentration of CO gas in the system.

Solution

Step 1: (a) Increasing the pressure by decreasing the volume of the container will

cause the system to shift towards the side with fewer gas molecules to decrease

the pressure. In this case, there are 3 gas molecules on the left side and 2 gas

molecules on the right side. Therefore, the equilibrium will shift to the right to

decrease the pressure.

Step 2: (b) Adding an inert gas to the system at constant volume will not

affect the position of equilibrium since the total pressure (and hence the partial

pressures of the reactants and products) will remain constant.

Step 3: (c) Increasing the concentration of CO gas in the system will cause

the equilibrium to shift to the right to counteract the change. According to Le

N2(g) + 3H2(g)⇌2NH3(g)

If the concentration of nitrogen gas is increased, explain how Le Chatelier’s

Principle can be used to predict the direction of the shift in equilibrium.

Solution

Step 1: According to Le Chatelier’s Principle, if the concentration of any re-

actant or product is changed, the system will shift in a direction that tends to

counteract that change and restore equilibrium.

Step 2: In this reaction, if the concentration of nitrogen gas is increased, the

system will try to counteract this change by shifting the equilibrium position

towards the products side. This means that more ammonia gas will be produced.

Step 3: The shift to the right (products side) occurs because the reaction

consumes nitrogen gas in order to produce ammonia. By shifting the equilib-

rium in this direction, the reaction can help alleviate the increase in nitrogen

concentration and restore equilibrium.

Step 4: Therefore, by applying Le Chatelier’s Principle, we predict that if

the concentration of nitrogen gas is increased, the reaction will shift to produce

more ammonia gas until a new equilibrium is established.

Question 3

Question

Consider the following reaction at equilibrium:

N2O4(g)⇌2NO2(g)

If the concentration of N2O4is doubled at constant temperature, explain

how Le Chatelier’s Principle predicts the shift in equilibrium and the resulting

effect on the equilibrium constant Kc.

Solution

Step 1: According to Le Chatelier’s Principle, when the concentration of one of

the reactants or products is changed, the system will adjust in such a way as to

counteract the change and re-establish a new equilibrium.

Step 2: Doubling the concentration of N2O4will shift the equilibrium to the

left to consume some of the excess N2O4.

Step 3: As a result of the shift to the left, the concentration of N2O4will

decrease, while the concentrations of NO2will increase.

Step 4: The equilibrium constant Kcwill not change with the change in

concentrations. Kcis a constant at a given temperature and changing the

concentrations of reactants or products does not change Kc.

Step 5: In summary, the equilibrium will shift to the left to use up the

excess N2O4, resulting in a decrease in its concentration and an increase in the

concentration of NO2. The equilibrium constant Kcwill remain the same.

Question 4

Question

Consider the equilibrium reaction:

2SO2(g) + O2(g)⇌2SO3(g) ∆H=−198 kJ

If the pressure on the system is increased, predict the direction in which the

equilibrium will shift and justify your answer.

Solution

Step 1: First, let’s analyze the effect of increasing pressure on the system.

According to Le Chatelier’s Principle, when the pressure is increased, the equi-

librium will shift towards the side of the reaction with fewer moles of gas to

counteract the increase in pressure.

Step 2: Let’s examine the number of moles of gas on each side of the reaction.

On the reactant side, we have 3 moles of gas (2SO2and O2). On the product

side, we have 2 moles of gas (2SO3).

Step 3: Since the product side has fewer moles of gas than the reactant side,

increasing the pressure will cause the equilibrium to shift towards the product

side to reduce the pressure on the system.

Step 4: Therefore, in response to an increase in pressure, the equilibrium

will shift to the right, favoring the formation of SO3.

Question 5

Question

Consider the reaction:

N2O4(g)⇌2NO2(g)

If the concentration of N2O4is doubled at constant temperature and pres-

sure, predict the direction in which the equilibrium will shift. Justify your

answer using Le Chatelier’s Principle.

Solution

To determine the direction in which the equilibrium will shift, we need to analyze

the effect of doubling the concentration of N2O4on the equilibrium system.

Step 1: Write the expression for the equilibrium constant. The

equilibrium constant expression for the reaction is given by:

Kc=[NO2]2

[N2O4]

Step 2: Analyze the effect of doubling the concentration of N2O4.

By doubling the concentration of N2O4, the initial concentration would become

2[N2O4]. Therefore, the reaction quotient would change to:

Qc=[NO2]2

2[N2O4]

Step 3: Apply Le Chatelier’s Principle. Since the reaction quotient

Qcis now greater than the equilibrium constant Kc, the reaction will shift to

the right to counteract the increase in N2O4concentration. This means that

the concentration of N2O4will decrease while the concentrations of NO2will

increase until a new equilibrium is established.

Therefore, the equilibrium will shift to the right when the concentration of

N2O4is doubled.

Question 6

Question

Consider the following equilibrium:

N2(g) + 3H2(g)⇌2NH3(g)

If the temperature of the system is increased, predict the direction in which

the equilibrium will shift and explain why.

Solution

Step 1: Le Chatelier’s Principle states that a system at equilibrium will respond

to a stress by shifting the equilibrium position in a direction that helps to relieve

the stress.

Step 2: Increasing the temperature of a reaction system is a stress because

heat is considered a reactant or a product in most reactions.

Step 3: In this case, the reaction is exothermic, because the forward reac-

tion releases heat. Therefore, adding heat to the system will favor the reverse

reaction (endothermic) to absorb the excess heat.

Step 4: The equilibrium will shift to the left to consume some of the added

heat, producing more N2 and H2 at the expense of NH3.

Step 5: Thus, when the temperature is increased, the equilibrium will shift

in the direction of the reactants to relieve the stress, resulting in an increase in

the concentration of N2 and H2, and a decrease in the concentration of NH3.

Question 7

Question

Consider the following equilibrium reaction:

2A(g) + B(g) ⇌3C(g)

If the concentration of substance A is increased, predict the effect on the

equilibrium position according to Le Chatelier’s Principle. Justify your answer

with a detailed explanation.

Solution

Step 1: Recall Le Chatelier’s Principle, which states that if a system at equi-

librium is subjected to a change in temperature, pressure, or concentration of

reactants/products, the system will shift its position of equilibrium to counter-

act the change and establish a new equilibrium state.

Step 2: In this case, if the concentration of substance A is increased, the

system will react to counteract this change and establish a new equilibrium

position.

Step 3: When the concentration of A is increased, according to Le Chate-

lier’s Principle, the equilibrium will shift to the right to consume some of the

additional A until a new equilibrium is reached.

Step 4: By shifting to the right, more B will be consumed to produce more

C until a new equilibrium is established.

Step 5: Consequently, the concentration of C will increase, while the con-

centrations of A and B will decrease.

Step 6: Therefore, increasing the concentration of substance A will lead to

an increase in the concentration of substance C and a decrease in the concen-

trations of substances A and B at the new equilibrium position.

Question 8

Question

Consider the exothermic reaction:

2A(g) + B(g) ⇌2C(g)

If the equilibrium constant Kcfor the reaction is 3.5 at a certain temperature,

and the equilibrium concentrations are [A] = 0.10 M, [B] = 0.20 M, and [C] =

0.30 M, how will the equilibrium shift if the volume of the container is decreased

at constant temperature?

Solution

Step 1: Write the expression for Kc:

Kc=[C]2

[A]2

·[B] = 3.5

Step 2: Calculate the initial reaction quotient Qc:

Qc=(0.30)2

(0.10)2·(0.20) = 4.5

Step 3: Compare Qcto Kcto determine the initial direction of the reaction:

- Since Qc> Kc, the reaction will shift to the left to reach equilibrium.

Step 4: If the volume of the container is decreased, the system will try

to counteract the change by favoring the reaction which produces fewer gas

molecules. In this case, the left side of the reaction has fewer gas molecules

than the right side.

Step 5: The shift to the left will continue until a new equilibrium is es-

tablished. The concentrations of A, B, and C will adjust accordingly, but the

equilibrium constant will remain the same.

Question 9

Question

Consider the following reaction at equilibrium:

N2O4(g)⇌2NO2(g)

If the pressure on the system is increased by decreasing the volume, predict

the direction of the shift according to Le Chatelier’s Principle. Justify your

answer.

Solution

1. According to Le Chatelier’s Principle, when a system at equilibrium is

disturbed by a change in temperature, pressure, or concentration, the

equilibrium position will shift to counteract the imposed change.

2. In this case, by decreasing the volume of the system (which increases the

pressure), the system tries to counteract this increase in pressure.

3. The system will shift in the direction that reduces the total number of gas

molecules, as this will help decrease the pressure.

4. In the given reaction, 1 mole of N2O4decomposes to form 2 moles of

NO2. Therefore, as the equilibrium shifts to the right (products), it will

consume more N2O4to decrease the total number of gas molecules.

5. Thus, the equilibrium will shift to the right to produce more NO2and

reduce the pressure caused by the decreased volume.

Question 10

Question

Consider the following reaction at equilibrium:

2 NOCl(g) ⇌2 NO(g) + Cl2(g)

If the pressure of the system is increased by decreasing the volume, pre-

dict the direction in which the equilibrium will shift and explain why using Le

Chatelier’s Principle.

Solution

Step 1: Identify the changes introduced to the system: The pressure of the

system is increased by decreasing the volume.

Step 2: Predict the direction of the equilibrium shift: According to Le

Chatelier’s Principle, when the pressure is increased, the system will shift in

the direction that decreases the total number of gas molecules.

Step 3: Analyze the stoichiometry of the reaction: On the reactant side of

the reaction, there are 3 gas molecules (2 NOCl) and on the product side of the

reaction, there are 3 gas molecules (2 NO + Cl2).

Step 4: Determine the direction of the equilibrium shift: Since both the reac-

tant and product side of the reaction contain the same number of gas molecules,

changing the pressure by decreasing the volume will not favor either the reac-

tants or products. The equilibrium will not shift in either direction in response

to the change in pressure.

Question 11

Question

Consider the following reaction at equilibrium:

2 SO2(g)+O2(g)⇌2SO3(g)

If the temperature of the system is increased, predict the direction in which the

equilibrium will shift according to Le Chatelier’s Principle.

Solution

Step 1: When the temperature of the system is increased, the equilibrium will

shift in the direction that absorbs heat.

Step 2: In this reaction, the forward reaction is exothermic (heat is released)

and the reverse reaction is endothermic (heat is absorbed).

Step 3: Increasing the temperature of the system will favor the reaction that

absorbs heat (endothermic reaction).

Step 4: Therefore, the equilibrium will shift to the right (towards the prod-

ucts) to absorb the excess heat, increasing the concentration of SO3and main-

taining equilibrium.

Question 12

Question

Consider the following reaction at equilibrium:

2 SO2(g) + O2(g) ⇌2SO3(g)

Explain how the equilibrium will shift if the pressure of the system is in-

creased. Justify your answer using Le Chatelier’s Principle.

Solution

To understand how the equilibrium will shift if the pressure of the system is

increased, we need to consider the effect of pressure on the system.

Step 1: When the pressure is increased, according to Le Chatelier’s Princi-

ple, the system will shift in a way that minimizes the change in pressure.

Step 2: In this reaction, there are a total of 3 moles of gas on the reactant

side and 2 moles of gas on the product side. Therefore, increasing the pressure

will cause the system to shift towards the side with fewer moles of gas to reduce

the pressure.

Step 3: Since the reactant side has more moles of gas than the product

side, the equilibrium will shift to the right to decrease the pressure. This means

that more SO3 will be formed from SO2 and O2.

Step 4: Therefore, increasing the pressure will favor the formation of more

SO3 at equilibrium in order to minimize the change in pressure in the system.

Question 13

Question

Consider the reaction:

N2O4(g)⇌2NO2(g)

If the pressure is increased by compressing the system, predict the direc-

tion in which the equilibrium will shift and explain why using Le Chatelier’s

Principle.

Solution

Step 1: When the pressure is increased by compressing the system, according

to Le Chatelier’s Principle, the system will shift in the direction that reduces

the total number of moles of gas molecules.

Step 2: In the given reaction, on the reactant side, there is 1 mole of N2O4

and on the product side, there are 2 moles of NO2. Therefore, decreasing the

number of moles of gas molecules would shift the equilibrium towards the side

with fewer moles to relieve the pressure.

Step 3: Since the products side has more moles of gas molecules, the equi-

librium will shift to the left, favoring the formation of N2O4, to reduce the total

pressure.

Therefore, if the pressure is increased by compressing the system, the equi-

librium will shift to the left, towards the formation of more N2O4.

Question 14

Question

Consider the reaction:

2SO2(g)+O2(g)⇌2SO3(g)

What will happen to the equilibrium position if the volume of the container

is decreased?

Solution

Le Chatelier’s Principle states that if a system at equilibrium is disturbed by

a change in conditions (such as concentration, temperature, or pressure), the

system will shift its equilibrium position to counteract the effect of the distur-

bance.

Step 1: Decreasing the volume of the container will increase the total pres-

sure inside the container.

Step 2: Since there are more moles of gas on the reactant side of the reaction

(2SO2(g)+O2(g)) than on the product side (2SO3(g)), decreasing the volume

will favor the side of the reaction with fewer moles of gas to reduce the pressure.

Step 3: Therefore, the equilibrium will shift to the left, consuming some of

the reactants (SO2and O2) to produce more products (SO3).

Step 4: As a result, the concentrations of SO2and O2will decrease, while

the concentration of SO3will increase to re-establish equilibrium.

Thus, the equilibrium position will shift to the left in response to the decrease

in volume of the container.