Equilibrium in Chemical Reactions: Interactive Quizzes and Learning

Question 1

In a reversible chemical reaction at equilibrium, what is the effect of a catalyst on the reaction rate and equilibrium position?

Accepted Answer

A catalyst speeds up both the forward and reverse reactions without affecting the equilibrium position.

Answer

A catalyst increases the rate of the forward reaction only.

Answer

A catalyst shifts the equilibrium position towards the products.

Answer

A catalyst decreases the activation energy of the forward reaction only.

Question 2

Why do the units of the equilibrium constant vary for different equilibrium reactions?

Accepted Answer

The units of the equilibrium constant depend on the units of the reactants and products in the reaction.

Answer

The units of the equilibrium constant are always dimensionless.

Answer

The units of the equilibrium constant do not affect its value.

Question 3

When a chemical reaction is in equilibrium at a specific temperature, what happens to the equilibrium position if the temperature is decreased?

Accepted Answer

The equilibrium shifts left, favoring the reactants.

Answer

The equilibrium shifts right, favoring the products.

Answer

The equilibrium remains unchanged.

Answer

The equilibrium constant increases.

Question 4

How does equilibrium relate to the principles of thermodynamics? Explain the specific roles of enthalpy, entropy, and Gibbs free energy in determining equilibrium positions.

Accepted Answer

Equilibrium is a state of minimum free energy, and the equilibrium position shifts towards the side with the lowest Gibbs free energy.

Answer

Equilibrium is a state of maximum disorder, and the equilibrium position shifts towards the side with the highest entropy.

Answer

Equilibrium is a state of maximum enthalpy, and the equilibrium position shifts towards the side with the highest enthalpy.

Answer

Equilibrium is a state of constant change, and the equilibrium position shifts randomly.

Question 5

In a reversible reaction, like 2SO2(g) + O2(g) ⇌ 2SO3(g), both forward and reverse reactions occur continuously. How does this observation demonstrate the dynamic nature of equilibrium?

Accepted Answer

The forward and reverse reactions proceed at equal rates, keeping the concentrations of reactants and products constant.

Answer

The reactant concentrations decrease while the product concentrations increase over time.

Answer

The reaction proceeds to completion, converting all reactants into products.

Question 6

In the reaction A + B ⇌ C + D, the equilibrium constant (Kc) at 298 K is 4.0. At equilibrium, what is the relationship between the concentrations of the reactants and products?

Accepted Answer

Kc = [C] x [D] / [A] x [B]

Answer

Kc = [A] x [B] / [C] x [D]

Answer

Kc = [A] + [B] / [C] + [D]

Answer

Kc = [C] - [D] / [A] - [B]

Question 7

In a reversible reaction at equilibrium, the equilibrium constant (Kc) is equal to:

Accepted Answer

The ratio of the concentrations of the products to the reactants

Answer

The ratio of the concentrations of the reactants to the products

Answer

The sum of the concentrations of the reactants and products

Answer

Zero

Question 8

Which of the following reactions is NOT an equilibrium reaction?

Accepted Answer

NaOH + HCl → NaCl + H2O

Answer

H2 + O2 → H2O

Answer

CO + O2 → CO2

Answer

2NO2 → N2O4

Question 9

What happens to the rate of the forward reaction when the concentration of the products increases?

Accepted Answer

Decreases

Answer

Increases

Answer

Remains the same

Answer

Cannot be determined

Question 10

Which of the following is a common method for separating a mixture of two immiscible liquids?

Accepted Answer

Extraction

Answer

Distillation

Answer

Chromatography

Answer

Filtration

Question 11

What is the role of a catalyst in an equilibrium reaction?

Accepted Answer

To decrease the activation energy

Answer

To increase the equilibrium constant

Answer

To change the concentrations of the reactants and products

Answer

To stop the reaction from occurring

Question 12

Which of the following is NOT a factor that can influence the equilibrium position of a reaction?

Accepted Answer

Wavelength of light

Answer

Temperature

Answer

Pressure

Answer

Concentration

Question 13

Which of the following reactions is NOT in equilibrium?

Accepted Answer

NaOH(aq) + HCl(aq) -> NaCl(aq) + H2O(l)

Answer

CO(g) + H2O(g) <=> CO2(g) + H2(g)

Answer

2NO(g) <=> N2(g) + O2(g)

Answer

Cu(OH)2(s) <=> Cu2+(aq) + 2OH-(aq)

Question 14

Which ion will shift the equilibrium of the reaction Cu2+(aq) + 2OH-(aq) <=> Cu(OH)2(s) to the right?

Accepted Answer

OH-

Answer

Na+

Answer

Cu2+

Answer

Cl-

Question 15

What is the main purpose of using a buffer solution in a chemical reaction?

Accepted Answer

Maintain a constant pH

Answer

Increase reaction rate

Answer

Decrease equilibrium constant

Answer

Prevent precipitation

Question 16

Consider the following reaction at equilibrium:
2NO2(g) ⇌ N2O4(g)
If the concentration of NO2 is increased, what will occur?

Accepted Answer

The concentration of N2O4 will increase

Answer

The concentration of N2O4 will decrease

Answer

The equilibrium position will shift to the left

Answer

The equilibrium position will remain unchanged

Question 17

What is the forward reaction for the following equilibrium?

Accepted Answer

CO + H2O ⇌ CO2 + H2

Answer

CO2 + H2 ⇌ CO + H2O

Answer

CO + 2H2O ⇌ CO2 + 3H2

Answer

CO2 + 3H2 ⇌ CO + 2H2O

Question 18

Which of the following is the correct unit for an equilibrium constant?

Accepted Answer

Unitless

Answer

M

Answer

M-1

Answer

mol L-1

Question 19

Which of the following factors does NOT influence the equilibrium position of a reaction?

Accepted Answer

Amount of catalyst

Answer

Concentrations of reactants

Answer

Concentrations of products

Answer

Temperature

Question 20

What is the function of a catalyst in an equilibrium reaction?

Accepted Answer

To lower the activation energy

Answer

To alter the equilibrium constant

Answer

To change the equilibrium position

Answer

To hinder the reaction

Question 21

What is the defining characteristic of a homogeneous equilibrium?

Accepted Answer

Exists in a single phase

Answer

Involves solely gases

Answer

Involves exclusively solids or liquids

Answer

Exists in multiple phases

Question 22

What is the pH of a solution with a hydrogen ion concentration of 1 × 10^-5 mol/dm^3?

Accepted Answer

5

Answer

3

Answer

7

Answer

9

Question 23

A sealed container contains the following reaction at equilibrium: CO (g) + 2 H2 (g) <=>  CH3OH (g). If hydrogen gas is added, the equilibrium will:

Accepted Answer

Shift right, increasing the concentration of CH3OH

Answer

Shift left, decreasing the concentration of CH3OH

Answer

Not shift, remaining at equilibrium

Answer

Shift to form more CO and H2

Question 24

Which of the following is NOT a factor that can affect the equilibrium of a chemical reaction?

Accepted Answer

Magnetic field strength

Answer

Temperature

Answer

Concentration of reactants

Answer

Presence of a catalyst

Question 25

Which of these reactions is an example of a heterogeneous equilibrium?

Accepted Answer

Dissolving carbon dioxide gas in water

Answer

Decomposition of hydrogen peroxide

Answer

Neutralization of sodium hydroxide with hydrochloric acid

Answer

Formation of ammonia from nitrogen and hydrogen gases

Question 26

Which among the following factors does not affect the equilibrium position of a reversible reaction?

Accepted Answer

Addition of a catalyst

Answer

Temperature

Answer

Pressure

Answer

Concentration of reactants

Question 27

In the following equilibrium reaction, which direction will the reaction shift to if the temperature is increased: CO(g) + 2H2(g) <=> CH3OH(g) + Heat

Accepted Answer

Right

Answer

Left

Answer

No shift

Question 28

Which of the following is a defining characteristic of a heterogeneous equilibrium reaction?

Accepted Answer

Involves different phases (e.g., solid, liquid, gas)

Answer

Involves only gases

Answer

Involves only liquids

Answer

Can be represented by a single equilibrium constant

Question 29

Which industrial process involves the application of equilibrium principles in the production of ammonia?

Accepted Answer

Haber process

Answer

Ostwald process

Answer

Contact process

Answer

Solvay process

Question 30

When an equilibrium reaction has reached equilibrium, what is the value of its equilibrium constant?

Accepted Answer

One

Answer

Zero

Answer

Greater than one

Answer

Less than one

Question 31

Which among the following is not a factor that can disturb an equilibrium?

Accepted Answer

Adding an inert gas

Answer

Changing the temperature

Answer

Adding a catalyst

Answer

Removing a product

Question 32

What is the relationship between the equilibrium constant and the extent of reaction? A large equilibrium constant indicates:

Accepted Answer

Reaction proceeds mostly in the forward direction

Answer

Reaction proceeds mostly in the reverse direction

Answer

Reaction has a small equilibrium constant

Answer

Reaction has a negative equilibrium constant

Question 33

How can the equilibrium constant help determine the best conditions for producing the most of a desired product in an industrial process?

Accepted Answer

By finding the conditions that move the equilibrium towards the desired product

Answer

By predicting the exact molar ratio of reactants needed

Answer

By making sure the reaction finishes in the shortest amount of time possible

Question 34

According to Le Chatelier's principle, which factor does NOT affect the equilibrium position of a reaction?

Accepted Answer

Adding a catalyst

Answer

Adding a reactant

Answer

Changing the temperature

Answer

Changing the volume of the reaction

Question 35

In a chemical reaction at equilibrium, what is true about the forward and reverse reactions?

Accepted Answer

They occur at the same rate.

Answer

They do not occur.

Answer

The forward reaction is faster than the reverse reaction.

Answer

The reverse reaction is faster than the forward reaction.

Question 36

What is the value of the equilibrium constant (Kc) for a reaction that is at equilibrium?

Accepted Answer

Greater than zero

Answer

Zero

Answer

Less than zero

Answer

Varies depending on the temperature

Question 37

Which type of equilibrium reaction is represented by the following equation: CaCO3(s) ⇌ CaO(s) + CO2(g)?

Accepted Answer

Heterogeneous

Answer

Homogeneous

Answer

Physical

Answer

Acid-base

Question 38

Which application of equilibrium is used in the production of ammonia?

Accepted Answer

Haber process

Answer

Contact process

Answer

Ostwald process

Answer

Solvay process

Question 39

What is the effect of decreasing the temperature on the equilibrium constant for an exothermic reaction?

Accepted Answer

Decreases

Answer

Increases

Answer

Remains constant

Answer

Cannot be determined

Question 40

What is the role of a catalyst in an equilibrium reaction?

Accepted Answer

It speeds up both the forward and reverse reactions equally.

Answer

It speeds up the forward reaction only.

Answer

It speeds up the reverse reaction only.

Answer

It changes the equilibrium position.

Question 41

How does increasing the temperature affect the equilibrium position of the reaction N2(g) + 3H2(g) <=> 2NH3(g) + heat?

Accepted Answer

Shifts the equilibrium to the right (products favored)

Answer

Shifts the equilibrium to the left (reactants favored)

Answer

No change in equilibrium position

Answer

Cannot be determined

Question 42

Which action will shift the equilibrium of the reaction CO(g) + 2H2(g) <=> CH3OH(g) to the left?

Accepted Answer

Decreasing the concentration of CO

Answer

Increasing the concentration of H2

Answer

Increasing the temperature

Answer

Adding a catalyst

Question 43

Identify the type of equilibrium reaction represented by the equation: CH3COOH(aq) + H2O(l) <=> H3O+(aq) + CH3COO-(aq)

Accepted Answer

Acid-base

Answer

Precipitation

Answer

Gas-liquid

Answer

Homogeneous

Question 44

What is the value of the equilibrium constant for a reaction that has reached equilibrium?

Accepted Answer

1

Answer

0

Answer

Greater than 1

Answer

Less than 1

Question 45

Which characteristic defines a dynamic equilibrium?

Accepted Answer

Equal rates of forward and reverse reactions

Answer

Constant concentrations of reactants and products

Answer

Closed system

Answer

Exothermic reaction

Question 46

Which factor does not influence the equilibrium constant of a reaction?

Accepted Answer

Volume of the reaction vessel

Answer

Temperature

Answer

Concentration of reactants and products

Answer

Presence of a catalyst

Question 47

For the reaction: 2A + B ⇌ C, the equilibrium constant expression is:

Accepted Answer

[A]^2[B]/[C]

Answer

[C]/[A]^2[B]

Answer

[A][B]^2/[C]

Answer

[C]/[A][B]^2

Question 48

In a closed system at equilibrium, the forward and reverse reaction rates are:

Accepted Answer

Equal.

Answer

The forward rate is greater than the reverse rate.

Answer

The reverse rate is greater than the forward rate.

Answer

Both zero.

Question 49

Which of these is NOT an application of equilibrium in industry?

Accepted Answer

Combustion

Answer

The Haber process

Answer

The Contact process

Answer

Electrolysis

Question 50

For a reaction that proceeds to completion, the equilibrium constant is:

Accepted Answer

Infinity

Answer

0

Answer

1

Answer

Cannot be determined

Question 51

What does a catalyst do in an equilibrium reaction?

Accepted Answer

Decreases the activation energy of the reaction.

Answer

Increases the activation energy of the reaction.

Answer

Changes the equilibrium constant.

Answer

Prevents the reaction from reaching equilibrium.

Question 52

The main difference between a homogeneous and a heterogeneous equilibrium is:

Accepted Answer

The phases of the reactants and products are the same / different.

Answer

The equilibrium constant is different / the same for both.

Answer

The reaction rate is different / the same for both.

Answer

The temperature dependence is different / the same for both.

Question 53

In a dynamic equilibrium, how do the concentrations of reactants and products change over time?

Accepted Answer

Reactant and product concentrations initially change, but eventually reach constant values that remain stable over time.

Answer

Reactant concentrations decrease, while product concentrations increase until one reactant is exhausted.

Answer

Reactant and product concentrations fluctuate randomly, never reaching a stable point.

Question 54

Equilibrium reactions involve:

Accepted Answer

Simultaneous occurrence of forward and reverse reactions at equal rates.

Answer

Only forward reactions occurring.

Answer

Complete consumption of reactants forming no products.

Answer

Unchanging concentrations of reactants and products over time.

Question 55

Which factor will shift the equilibrium of an exothermic reaction towards the product side?

Accepted Answer

Increase in temperature

Answer

Decrease in temperature

Answer

Increase in pressure

Answer

Addition of a catalyst

Question 56

The primary function of a buffer in an equilibrium solution is to:

Accepted Answer

Maintain a stable pH

Answer

Increase the equilibrium constant

Answer

Shift the equilibrium to the right

Answer

Decrease the reaction rate

Question 57

Equilibrium in a chemical reaction occurs when:

Accepted Answer

The rate of the forward reaction is equal to the rate of the reverse reaction

Answer

The concentrations of all reactants and products are zero

Answer

The Gibbs free energy of the reaction is negative

Answer

The entropy of the system is minimum

Question 58

The equilibrium constant (Kc) is a measure of:

Accepted Answer

The equilibrium concentrations of reactants and products

Answer

The relative rates of forward and reverse reactions

Answer

The extent to which a reaction proceeds

Answer

The temperature at which the reaction occurs

Question 59

Which factor does NOT affect the equilibrium position of a reaction?

Accepted Answer

Identity of the reactants and products

Answer

Temperature

Answer

Pressure (for reactions involving gases)

Answer

Concentration of reactants and products

Question 60

An exothermic reaction has a negative enthalpy change. How will increasing temperature affect the equilibrium?

Accepted Answer

Shift to the left (exothermic = heat released)

Answer

Shift to the right (endothermic = heat absorbed)

Answer

No effect

Answer

Cannot be determined

Question 61

Heterogeneous equilibria involve reactions between:

Accepted Answer

A solid and a gas

Answer

Two solutions

Answer

Two gases

Answer

Two liquids

Question 62

Which process involves the application of equilibrium in the production of ammonia?

Accepted Answer

Haber Process

Answer

Contact Process

Answer

Ostwald Process

Answer

Le Blanc Process

Question 63

The equilibrium constant for a gas-phase reaction (Kp) is:

Accepted Answer

Related to Kc by the ideal gas constant (R)

Answer

Equal to the equilibrium constant for the same reaction in solution (Kc)

Answer

Always greater than Kc

Answer

Always less than Kc

Question 64

Which statement about the equilibrium constant is correct?

Accepted Answer

It is a constant for a given reaction at a fixed temperature

Answer

It depends on the initial concentrations of the reactants

Answer

It can be negative

Answer

It is a measure of the rate of the reaction