Equilibrium

Question 1

what is dynamic equilibrium

Answer 1

• when the rate of the forward reaction and backward reaction are equal
• when the concentration of reactants and products is constant

Question 2

what is Le Chateliers Principle

Answer 2

if an external condition is changed the equilibrium will shift position to oppose the change

Question 3

how do changes in temperature affect the equilibrium

Answer 3

if temperature is increased…
* equilibirum position shifts to favour the endothermic reaction
if temperature is decreased…
* equilibrium position shifts to favour the exothermic reaction

Question 4

how do changes in gas pressure affect the equilibrium

Answer 4

if pressure is increased…
* the equilibrium shifts to favour the direction that produces fewer moles
if pressure is decreased…
* the equilibirum shifts to favour the direction that produces more moles

Question 5

how do changes in concentration affect equilibrium

Answer 5

if concentration of reactants is increased…
* equilibrium shifts right (higher product yield)
if concentration of reactants is decreased…
* equilibrium shifts left (lower product yield)

Question 6

how does a catalyst affect equilibrium

Answer 6

• no effect of position of equilibrium
• only affect time taken to reach equilibrium

Question 7

what is the constant Kc

Answer 7

At equilibrium, the ratio of concentration of products and reactants is constant The value of this ratio is called the equilibrium constant, Kc

Question 8

what does it mean if Kc > 1

Answer 8

the concentration of products is greater than the concentration of the reactants and we say that the equilibrium lies to the right hand side

Question 9

what does it mean if Kc < 1

Answer 9

the concentration of reactants is greater than the concentration of the products and we say that the equilibrium lies to the left right side

Question 10

what external conditions affect Kc

Answer 10

• affected by temperature
• not affected by change in concentration, pressure or adding a catalyst

Question 11

what happens to Kc when you increase temperature

Answer 11

• for exothermic reactions increasing the temperature decreases the equilibrium constant
• for endothermic reactions increasing the temperature increases the equiibrium constant