Equilibrium

Question 0

What is dynamic equilibrium?

Answer 0

An equilibrium in which the rates of forward and reverse processes are equal.

Question 1

What is chemical equilibrium?

Answer 1

Chemical equilibrium is when the concentrations of all the reactants and products of a chemical reaction remain constant over time.

Question 2

Are all chemical equilibria dynamic equilibria?

Answer 2

Yes

Question 3

What is the equilibrium position?

Answer 3

The relative concentration of reactants and products in a chemical reaction system at equilibrium.

Question 4

What are reversible reactions?

Answer 4

Chemical reactions that proceed in both the forward and reverse directions.

Question 5

In which direction can equilibrium be reached?

Answer 5

An equilibrium position can be reached starting from the forward or reverse reaction.

Question 6

Is the equilibrium position the same starting from either side?

Answer 6

Yes

Question 7

What does ICE in i.c.e. Table stand for?

Answer 7

Initial concentrations, change in concentrations and equilibrium concentrations

Question 8

What is equilibrium law?

Answer 8

The mathematical description of a chemical system at equilibrium.

Question 9

What states are used in equilibrium law?

Answer 9

Gaseous and aqueous states only

Question 10

What is K?

Answer 10

K is the equilibrium constant, a numerical value that defines equilibrium law for a given system.

Question 11

Is K reported with units?

Answer 11

No

Question 12

Will the equilibrium constant always have the same value regardless of initial concentrations provided that all other variables are kept the same?

Answer 12

Yes

Question 13

Does K depend on temperature?

Answer 13

Yes

Question 14

If K represents the forward reaction, what does K’ (K prime) represent?

Answer 14

The reverse reaction. K’ = 1/K

Question 15

What is homogeneous equilibrium?

Answer 15

Chemical equilibrium in which all reactants and products are in the same state of matter.

Question 16

What is heterogeneous equilibrium?

Answer 16

When reactants and products are present in more than one state.

Question 17

Does the equilibrium position of heterogeneous equilibrium depend on the quantities of pure solids and liquids?

Answer 17

No, because the concentrations of pure solids and liquids do not change.

Question 18

Do solids and liquids appear in the equilibrium law equation?

Answer 18

No

Question 19

How can equilibrium positions be disturbed?

Answer 19

Through changes in pressure, temperature, concentration or a combination of these.

Question 20

What is Le Châtelier’s Principle?

Answer 20

When a chemical system at equilibrium is disturbed by a change in a property, the system adjusts in a way that opposes the change.

Question 21

What is an equilibrium shift?

Answer 21

An adjustment by a system at equilibrium that results in a change in the concentrations of reactants and products.

Question 22

What happens when K is far less than one?

Answer 22

The equilibrium shifts far to the right favouring products

Question 23

What happens when K is about equal to one?

Answer 23

The concentration of products is about equal to that of reactants

Question 24

What happens when K is much higher than 1?

Answer 24

The equilibrium shifts far to the left favouring reactants.

Question 25

What happens when a reactant is added to a reaction?

Answer 25

The equilibrium shifts to the right, favouring products to oppose the change. (More product needs to be created)

Question 26

What happens when some reactant is removed from a reaction?

Answer 26

The equilibrium shifts to the left (towards reactants) to oppose the change and produce more of the reactant

Question 27

What happens when the concentration of a reactant increases in a reaction?

Answer 27

The equilibrium shifts to the right because the number of successful collisions for the forward reaction increases (and vice versa)

Question 28

What happens when the concentration of products increases?

Answer 28

The equilibrium shifts to the left to create more reactants causing the reverse reaction rate to increase.

Question 29

In an endothermic reaction, when would the equilibrium shift left?

Answer 29

When the reaction is cooled (thermal energy removed). (It is like having a reactant removed) therefore reaction shifts left.

Question 30

In an endothermic reaction, when would equilibrium shift right?

Answer 30

If thermal energy is added.

Question 31

In an exothermic reaction, when would equilibrium shift right?

Answer 31

If thermal energy is removed (energy is a product), the equilibrium will shift right

Question 32

In an exothermic reaction, when will equilibrium shift left?

Answer 32

If thermal energy is added (since energy is a product, this will be like having too much product)

Question 33

When do pressure and volume have no effect on gases?

Answer 33

When there are the same number of moles on both sides.

Question 34

What happens in a gaseous reaction when volume decreases and pressure increases?

Answer 34

The equilibrium shifts to the side with less moles. (Vice versa is also correct).

Question 35

Do catalysts change equilibrium position?

Answer 35

No. But they help the reaction reach equilibrium much faster.

Question 36

What are inert gases?

Answer 36

Non-reactive gases (Noble gases).

Question 37

What are inert gases good for?

Answer 37

Increasing pressure causing more collisions.

Question 38

Does K change with concentration?

Answer 38

No

Question 39

What happens when Q is less than K?

Answer 39

Equilibrium shifts to the right till equilibrium is reached.

Question 40

What happens when Q is equal to K?

Answer 40

The reaction is at equilibrium. No shift.

Question 41

What happens when Q is greater than K?

Answer 41

Equilibrium shifts to the left until equilibrium is reached.

Question 42

Explain the Hundo Rule.

Answer 42

If the concentration to which x is added or subtracted is at least 100x greater than the value of K, then the simplifying assumption will give an error of less than 5% therefore valid.

Question 43

What is Ksp?

Answer 43

Ksp is K for a saturated solution.

Question 44

Is temperature always included when reporting Ksp?

Answer 44

Yes.

Question 45

What happens when Q is greater than Ksp?

Answer 45

Equilibrium shifts left; precipitate forms until solution reaches new equilibrium.

Question 46

What happens when Q is less than Ksp?

Answer 46

Equilibrium shifts right. No precipitate since solution is unsaturated.

Question 47

What happens when Q is equal to Ksp?

Answer 47

Solution is at equilibrium.

Question 48

What is called the common ion effect?

Answer 48

Lowering the solubility of an ionic compound by the addition of a common ion.