Equilibria

Question 1

Homogeneous equilibria

Answer 1

All reactants and products in the same state

Question 2

Heterogeneous equilibria

Answer 2

Products and reactants in mixed states (only use gaseous states in Kc calculation

Question 3

Kc calculation

Answer 3

[HA] / [A-] [H+]

Question 4

Mole fraction

Answer 4

The same as its proportion by volume to the total volume of gases in a gas mixture

Question 5

Mole fraction calculation

Answer 5

Number of miles of A/ total number of miles in gas mixture

Question 6

Partial pressure

Answer 6

The contribution that the gas makes towards the total pressure p. The some of the partial pressures is equal to the total pressure

Question 7

Partial pressure calculation

Answer 7

Mole fraction of A x total pressure p

Question 8

Kp calculation

Answer 8

p(HA) / p(A-) p(H+)

Question 9

K= 1

Answer 9

Indicates an equilibrium halfway between reactants and products

Question 10

K= 100

Answer 10

Indicates an equilibrium well in favour of the products

Question 11

K= 1x10^-2

Answer 11

Indicates an equilibrium well in favour of the reactants

Question 12

When does K change?

Answer 12

If the temperature changes

Question 13

What doesn’t effect K?

Answer 13

Concentration
Pressure
Presence of a catalyst

Question 14

Le chateliers principle

Answer 14

1) if concentration increases, equilibrium shifts to reduce that increase.
2) if pressure increases, equilibrium shifts towards the side with fewer gaseous moles
3) if temperature increases, equilibrium shifts in the endothermic direction

Question 15

Ectothermic reaction

Answer 15

Gives out energy

Question 16

Endothermic reactions

Answer 16

Takes in energy

Question 17

Increasing temperature in exothermic reactions

Answer 17

• equilibrium constant decreases
• decreases equilibrium yield of product
• equilibrium shifts left

Question 18

Effect of increasing temperature in Endothermic reaction

Answer 18

• equilibrium constant increases
• increases equilibrium yield of products
• equilibrium position shifts right

Question 19

What effect do catalysts have?

Answer 19

• Affect the rate of a chemical reaction but not the position of equilibrium.
• speed up both the forward and reverse reactions by the same factor
• equilibrium is reached faster but position is the same

Question 20

How the concentration changes to return the ratio back to the Kc value

Answer 20

If the concentration of product increases, the concentration of reactant decreases.
= equilibrium shifts right

Question 21

Doubling the pressure of the products and reactants in an equilibrium

Answer 21

Double pressure= double of partial pressures and concentrations of both.
Partial pressure of products must decrease and of reactants must increase.
=Equilibrium shifts left