CI 2 - Equilibrium

Question 1

What is the equilibrium constant?

Answer 1

The equilibrium constant tells you the position of equilibrium of a reaction
The magnitude indicates whether there are more reactants of products in the system

Question 2

How does temperature affect the magnitude of the equilibrium constant?

Answer 2

• If the forward reaction is exothermic, increasing the temperature shifts the position of equilibrium to the left so Kc decreases
• If the forward reaction is endothermic, increasing the temperature shifts the equilibrium to the right so Kc increases

Question 3

How does pressure affect the magnitude of the equilibrium constant?

Answer 3

Kc remains the same:
- For example, doubling the pressure will double both the partial pressures and concentrations of the species on both sides of the equilibrium
- The system is no longer in equilibrium so partial pressures of reactants and products must change to keep Kc the same
- New equilibrium position will be reached whereby Kc is restored (as ratio of Kc expression is the same as before)

Question 4

Does the addition of a catalyst affect the position of equilibrium?

Answer 4

No, a catalyst doesn’t affect the position of equilibrium
It does however increase the rate of both the forward and reverse reactions

Question 5

Why may temperatures used in industry be different than expected?

Answer 5

A low temperature may give a greater yield for a particular product in a reversible reaction, however this will result in a slow rate of reaction and so a higher temperature may be used to strike a balance between yield and rate

Question 6

Why may the pressure used in industry be different than expected?

Answer 6

A high pressure may give a greater yield for a particular product in a reversible reaction, however high pressures can be dangerous and expensive and so a lower pressure may be used

Question 7

What is a homogeneous equilibria?

Answer 7

A homogeneous equilibrium contains species that are all the same state/phase

Question 8

What is a heterogeneous equilibria?

Answer 8

A heterogeneous equilibrium contains reactants and products that are in different states/phases

Question 9

How do you calculate Kc?

Answer 9

The product of the concentrations of products to the power of their balancing number divided by the product of the concentrations of the reactants to the power of their balancing number will equal the equilibrium constant