equilibrium I

Question 1

“How is reversibility indicated in a chemical reaction?”

Answer 1

“Reversibility is indicated in a chemical reaction by the symbol ⇌.

Question 2

What happens to the forward reaction as the reactants are consumed?

Answer 2

The forward reaction slows down.
Example: In the reaction A + B ⇌ C, as A and B are consumed, the rate of the forward reaction decreases

Question 3

What happens to the reverse reaction as more product is formed?

Answer 3

The reverse reaction speeds up.
Example: In the reaction A + B ⇌ C, as more of product C is formed, the rate of the reverse reaction increases.

Question 4

What is dynamic equilibrium?

Answer 4

Dynamic equilibrium is a state in which the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.

Question 5

In what type of system does dynamic equilibrium occur?

Answer 5

Dynamic equilibrium can only occur in a closed system, where nothing can enter or leave.

Question 6

What does the equilibrium constant, Kc, indicate?

Answer 6

The equilibrium constant, Kc, gives an idea of how far to the left or right the equilibrium is.

Question 7

How is the equilibrium constant, Kc, calculated?

Answer 7

The equilibrium constant, Kc, is calculated using the equilibrium concentrations of the reactants and products in a system.

Question 8

What defines a homogeneous system?

Answer 8

A homogeneous system is a system in which everything is in the same physical state.

Question 9

What is included in the expression for the equilibrium constant, Kc, for homogeneous equilibria?

Answer 9

For homogeneous equilibria, all the products and reactants are included in the expression for Kc.

Question 10

What is the expression for the equilibrium constant, Kc, for the reaction aA + bB ⇌ dD + eE?

Answer 10

Kc = [D]^d[E]^e / [A]^a[B]^b.

Question 11

What is a heterogeneous system?

Answer 11

In a heterogeneous system, not everything is in the same physical state.

Question 12

What is excluded from the expression for Kc in heterogeneous equilibria?

Answer 12

In heterogeneous equilibria, solids or pure liquids are excluded from the expression for Kc because their concentrations remain constant throughout the reaction.

Question 13

What is the role of catalysts in chemical equilibrium?

Answer 13

Catalysts do not affect the equilibrium concentrations of products or reactants. Instead, they speed up the rate at which dynamic equilibrium is achieved.

Question 14

Are catalysts included in equilibrium constant expressions?

Answer 14

No, catalysts are not included

Question 15

Why aren’t catalysts included in equilibrium constant expressions?

Answer 15

Catalysts do not alter the equilibrium concentrations of products or reactants; they only affect the rate of the reaction.

Question 16

How do catalysts affect dynamic equilibrium?

Answer 16

Catalysts speed up the rate at which dynamic equilibrium is reached by providing an alternative reaction pathway with lower activation energy.

Question 17

What happens when you change concentration, pressure, or temperature in a reversible reaction?

Answer 17

The equilibrium position shifts to attain a new balance, resulting in different amounts of reactants and products at equilibrium.

Question 18

Why does altering these factors change equilibrium position?

Answer 18

Equilibrium responds to changes to maintain a stable ratio of reactants to products, ensuring minimal disruption to the system.

Question 19

what does Le Chateliers principle tell you

Answer 19

If there’s a change in concentration, pressure or temperature,
the equilibrium will move to help counteract the change

Question 20

What happens to the equilibrium position when the concentration of a reactant is increased?

Answer 20

the equilibrium shifts to the right, favouring the production of more product to counteract the increase in reactant concentration.

Question 21

How does changing the pressure affect the equilibrium position in a gas-phase reaction?

Answer 21

Increasing the pressure shifts the equilibrium to the side with fewer gas molecules, reducing the pressure.
Decreasing the pressure shifts the equilibrium to the side with more gas molecules, raising the pressure again.

Question 22

How does increasing the temperature affect the equilibrium position in an endothermic reaction?

Answer 22

Increasing the temperature shifts the equilibrium in the endothermic (positive ∆H) direction to absorb the added heat.

Question 23

How does decreasing the temperature affect the equilibrium position in an exothermic reaction?

Answer 23

Decreasing the temperature shifts the equilibrium in the exothermic (negative ∆H) direction to compensate for the lost heat.

Question 24

What relationship exists between the endothermic and exothermic nature of the forward and reverse reactions?

Answer 24

f the forward reaction is endothermic, the reverse reaction will be exothermic, and vice versa.

Question 25

What approach should you take during an exam when asked to determine the optimal conditions for an industrial process to achieve a balance between high rate and high yield?

Answer 25

Examine any provided data, such as the enthalpy change of reaction.
Apply Le Chatelier’s principle to predict how changes in conditions will affect the equilibrium position.
Determine the conditions that will maximize both the rate and yield of the desired product.