Kc constant

Question 1

What is Kc?

Answer 1

The equilibrium constant
Gives us an idea of how far left or to the right the position of equilibrium is

Question 2

What 2 methods are used to calculate the Kc?

Answer 2

Heterogeneous equilibrium
Homogeneous equilibrium

Question 3

Homogeneous equilibrium

Answer 3

Calculating the Kc when all reactants and products are in the same state

Question 4

What values are used in homogeneous equilibrium?

Answer 4

ALL

Question 5

Kc expression

Answer 5

[Conc of product]
————————
[conc of reactant]
May be multiple
To the power of the stoichoometry

Question 6

Heterogeneous equilibrium

Answer 6

Calculating the Kc when not everything is in the same physical state

Question 7

What values are used in heterogeneous equilibrium?

Answer 7

DONT INCLUDE PURE LIQUIDS (l)
DONT INCLUDE SOLIDS (s)

Question 8

Why not use liquids or solids in equilibrium constant?

Answer 8

Because their concentrations stay constant throughout the reaction

Question 9

What factors affect the equilibrium constant?

Answer 9

None of them except temperature

Question 10

What happens if equilibrium constant has increased?

Answer 10

The position of equilibrium shifts to favour the forward reaction

Question 11

What happens if equilibrium constant decreases?

Answer 11

The position of equilibrium shifts to favour the backwards reaction

Question 12

Why does the position of equilibrium shifting right due to changes in temperature mean the Kc value increases?

Answer 12

Because then the concentration of products has increased and the concentration of reactants has decreased
So the equilibrium constant fraction gets larger on top than bottom (increased value)

Question 13

If increasing the temperature causes the Kc to decrease, what does this tell us?

Answer 13

This means the position of equilibrium has shifted to the left because the Kc has decreased (fraction smaller on top than bottom in constant)
So therefore the backwards reaction is endothermic (shifted this way when temp increases)
And forwards reaction is exothermic

Question 14

Why does changing concentration not effect Kc value?

Answer 14

Because the position of equilibrium shifts in order to oppose the increase of one reactants’s conc
So this will reach a balance in order to revert the Kc value back to how it originally was by increasing the conc of reactants on other side