Chemical Equilibrium Review

Question 1

What is dynamic equilibrium in a chemical reaction?

Answer 1

A state in which no net change occurs because there are two opposing processes occurring at the same rate.

Rogers, Chem for Eng, Pg. 259

Question 2

In chemistry what does something in square brackets represent?

Answer 2

The concentration of a substance in units of moles per liter or molarity.

Rogers, Chem for Eng, Pg. 260

Question 3

What variables is the equilibrium constant dependent upon?

Answer 3

Temperature, initial concentrations, pressure, and the presence of a catalyst.

Rogers, Chem for Eng, Pg. 260

Question 4

True or False

The equilibrium constant is non-dimensional.

Answer 4

True

Rogers, Chem for Eng, Pg. 260

Question 5

If the equilibrium constant is very large, then the equilibrium mixture contains mostly ______.

Answer 5

Products

Rogers, Chem for Eng, Pg. 261

Question 6

If the equilibrium constant is very small, then the equilibrium mixture contains mostly ________.

Answer 6

Reactants.

Rogers, Chem for Eng, Pg. 261

Question 7

True or False
At a given temperature, the same concentration ratio will always be obtained for a given reaction regardless of the initial concentration of reactants and products.

Answer 7

True.

Rogers, Chem for Eng, Pg. 261

Question 8

What is meant by the term “forward reaction?”

Answer 8

The amount of reactants decreases while the amount of products increases.

Rogers, Chem for Eng, Pg. 261

Question 9

What is meant by the term, “reverse reaction?”

Answer 9

The amount of reactants increases while the amount of products decreases.

Rogers, Chem for Eng, Pg. 261

Question 10

The value of an equilibrium constant at a given temperature is _____ of initial concentrations.

Answer 10

Independent.

Rogers, Chem for Eng, Pg. 262

Question 11

What is the benefit of knowing the reaction quotient?

Answer 11

Knowing the reaction quotient allows one to determine whether or not a chemical reaction will occur in the forward or reverse direction.

Rogers, Chem for Eng, Pg. 262

Question 12

If the reaction quotient is less than the equilibrium constant, how will the reaction proceed?

Answer 12

In the forward direction.

Rogers, Chem for Eng, Pg. 263

Question 13

If the reaction quotient is greater than the equilibrium constant, how will the reaction proceed?

Answer 13

In the reverse direction.

Rogers, Chem for Eng, Pg. 263

Question 14

If the reaction quotient is equal to the equilibrium constant how will the reaction proceed?

Answer 14

The reaction is at equilibrium.

Rogers, Chem for Eng, Pg. 263

Question 15

What is the definition of concentration?

Answer 15

It is the number of moles divided by volume.

Rogers, Chem for Eng, Pg. 268

Question 16

What is a homogeneous equilibrium state?

Answer 16

A homogeneous equilibrium is one in which all of the reactants and products are the same phase.

Rogers, Chem for Eng, Pg. 269

Question 17

What is a heterogeneous equilibrium state?

Answer 17

A heterogeneous equilibrium contains a solid or liquid in contact with substances and different phases.

Rogers, Chem for Eng, Pg. 269

Question 18

In a heterogeneous equilibrium, any solid or liquid is _____ from the Kc or Kp equations.

Answer 18

Omitted

Rogers, Chem for Eng, Pg. 269

Question 19

True or False

Aqueous solutions are included in the KC or KP equations.

Answer 19

True.

Rogers, Chem for Eng, Pg. 269

Question 20

Why are all solids and liquids omitted from the Kc/Kp equations?

Answer 20

Because the concentration of any solid or liquid is an intensive property.

Rogers, Chem for Eng, Pg. 269

Question 21

The mass of a solid or liquid can change during the course of a reaction, however, the concentration (in mol/L) does _______ change.

Answer 21

not

Rogers, Chem for Eng, Pg. 269

Question 22

True or False?
The equilibrium position does not depend on how much solid or liquid is present. As long as there is some solid or liquid a system can achieve equilibrium.

Answer 22

True

Rogers, Chem for Eng, Pg. 270

Question 23

What is Le Chatelier’s Principle?

Answer 23

It states that if a system at equilibrium is disturbed by changes in concentration, pressure, or temperature, the system will respond by shifting its equilibrium position in a direction that will counter the disturbance.

Rogers, Chem for Eng, Pg. 283

Question 24

If products are removed or if reactants are added what will be the relationship between the equilibrium constant and the reaction product? How will the reaction proceed?

Answer 24

Qc < Kc
In the forward direction

Rogers, Chem for Eng, Pg. 284

Question 25

If reactants are removed or if products are added to an equilibrium mixture, the magnitude of Qc ______. this causes the equilibrium to shift _______, and a _____ reaction occurs.

Answer 25

Increases left reverse Rogers, Chem for Eng, Pg. 284

Question 26

True or False An equilibrium will shift to the right (that is, in a forward direction) if the concentration on the reactant side is increased or if the concentration on the product side is decreased.

Answer 26

True Rogers, Chem for Eng, Pg. 285

Question 27

What are the three ways that changes in pressure player role in determining the equilibrium position of a gas phase reaction?

Answer 27

1. Changes in the partial pressure of a reactant or product gas. 2. Addition of a nonparticipating or inert gas. 3. Changing the volume of the container. Rogers, Chem for Eng, Pg. 286

Question 28

True or False The addition of nonparticipating gas in reaction increases the total pressure but it has no effect on individual partial pressures.

Answer 28

True Rogers, Chem for Eng, Pg. 286

Question 29

The addition of a non-participating substance (such as an inert gas) ______ affect the equilibrium position.

Answer 29

does not Rogers, Chem for Eng, Pg. 286

Question 30

Give a definition for partial pressure.

Answer 30

The pressure that an individual gas in a mixture of gases would exert if it were by itself. Rogers, Chem for Eng, Pg. 286

Question 31

What would happen if the volume of the container were decreased during a gas equilibrium reaction?

Answer 31

This would cause the total pressure to increase. Le Chatelier's principle suggests that a system will counter this increase by shifting to the side of the equation with fewer moles of gas. Rogers, Chem for Eng, Pg. 286

Question 32

What would happen if the volume of the container were increased during a gas equilibrium reaction?

Answer 32

Increasing the volume of the container causes the total pressure to decrease. The system responds to a decrease in pressure due to expansion by shifting to the side of the equation with more moles of gas. Rogers, Chem for Eng, Pg. 286

Question 33

True or False | Neither changes in temperature nor changes in concentration will change the equilibrium constant value.

Answer 33

False. Changing the temperature does change the equilibrium value. Rogers, Chem for Eng, Pg. 287

Question 34

An endothermic reaction will respond to an increase in temperature by _______.

Answer 34

Shifting to the right. The equilibrium mixture will contain more products and fewer reactants than the original one at a lower temperature. Rogers, Chem for Eng, Pg. 287

Question 35

When the temperature is lowered for an endothermic reaction at equilibrium their reaction ______.

Answer 35

Shifts to the left. The new equilibrium mixture will contain more reactants and fewer products at the lower temperature and the magnitude of the equilibrium constant decreases. Rogers, Chem for Eng, Pg. 287

Question 36

For an endothermic reaction, a change in temperature shifts the equilibrium ______ and ______ the magnitude of Keq.

Answer 36

to the right increases Rogers, Chem for Eng, Pg. 287

Question 37

When the temperature is lowered for an endothermic reaction at equilibrium the reaction shifts to the ______ and the magnitude of Keq ______.

Answer 37

left decreases Rogers, Chem for Eng, Pg. 287

Question 38

For an exothermic reaction, heat is written on the ______ side of the equation.

Answer 38

product. Rogers, Chem for Eng, Pg. 288

Question 39

For an exothermic reaction, heat is written on the ______ side of the equation.

Answer 39

Reactant. Rogers, Chem for Eng, Pg. 287

Question 40

Increasing the temperature of an exothermic reaction causes the equilibrium to shift to the _____, and _____ the equilibrium constant Keq.

Answer 40

left decreases Rogers, Chem for Eng, Pg. 288

Question 41

Decreasing the temperature of an exothermic reaction causes the equilibrium to shift to the ______, and _______ the equilibrium constant Keq.

Answer 41

right increases Rogers, Chem for Eng, Pg. 288

Question 42

True or False: The addition of a catalyst does not affect the final equilibrium position. A catalyst speeds up a reaction, and egg boiling it to reach equilibrium faster. However, it has no effect on the equilibrium amounts.

Answer 42

True. Rogers, Chem for Eng, Pg. 288

Question 43

True or False | in a heterogeneous equilibrium, changing the amount of solid or liquid does affect the equilibrium position.

Answer 43

False. It does affect the equilibrium position. Rogers, Chem for Eng, Pg. 288