Dynamic and Chemical Equilibrium

Dynamic Equilibrium

Dr Ahmed

Dynamic Equilibrium

• Define equilibrium and closed system

• Explain why the concentrations of chemicals remain constant in a dynamic equilibrium

• Explain how changing conditions of a system in dynamic equilibrium affects the RATE of the forward and reverse reaction

Equilibrium

• Equilibrium is reached when the rate of the forward reaction is ___________ to the rate of the backward reaction.

• In a CLOSED system

So if you have a reaction at equilibrium how can make more products?

Multiple Select

How can we increase the rate of reaction by only increasing frequency of collisions?

• Increase temperature

• Add a catalyst

• Increase concentration

• Increase pressure

• Increase surface area

Multiple Select

How can we increase the rate of reaction by increasing the energy of collisions?

• Increase temperature

• Add a catalyst

• Increase concentration

• Increase pressure

• Increase surface area

Multiple Select

How can we increase the rate of reaction by decreasing the activation energy?

• Increase temperature

• Add a catalyst

• Increase concentration

• Increase pressure

• Increase surface area

Le Chatelier's Principle

Whenever a change in conditions is introduced to a system at equilibrium the position of the equilibrium shifts to cancel out the change.

Effect of changing concetration

• If you increase the concentration of either a reactant or a product the equilibrium will shift to reverse that change

• ie A + 2B -> C + D

• If you increase the concentration of C the equilibrium will shift to the left

Effect of changing pressure

• If you increase the pressure the equilibrium will shift to reverse that change by favouring the side with less moles

• ie A + 2B -> C + D

• If you increase the pressure the equilibrium will shift right

Effect of changing temperature

• If you increase the temperature the equilibrium will shift to reverse that change by favouring the endothermic route

• ie A + 2B -> C + D (forward is exothermic)

• If you increase the temperature the equilibrium will shift left

Effect of adding a catalyst

• No shift

• Both reactions are increased by the same amount

Multiple Choice

Identify the incorrect statement about achieving equilibrium.

• achieved when product and reactant concentrations are equal

• achieved when forward and reverse reaction rates are same

• achieved when concentration of reactants is stable/constant

• achieved when concentration ratio of reactants to products becomes stable, thus fixing the equilibrium constant (equilibrium position)

Multiple Choice

For the following reaction:

2SO2 + O2 <-> 2SO3

If the concentration of SO2 is increased, the equilibrium position of the reaction will shift ___________.

• Left

• Right

• Both

• No change

Multiple Choice

LeChatelier's principle says that if a chemical reaction at equilibrium is disturbed by changing conditions, the reaction will...

• equal and opposite motion

• will adjust to amplify the changed conditions

• not change, because equilibrium means equal

• will shift appropriately to counteract the change.

Multiple Choice

In a reaction the forward reaction is exothermic.

Reducing temperature ...

• Favours the forward reaction

• Favours the backwards reactions

Multiple Choice

In this equation

N2(g) + 3H2(g) <-> 2NH3(g)

what happens if pressure is reduced

• Favours the forward reaction

• Favours the backwards reactions

Multiple Choice

In this equation

N2(g) + 3H2(g) <-> 2NH3(g)

what happens if concentration of hydrogen is increased?

• Favours the forward reaction

• Favours the backwards reactions

Multiple Choice

In this equation

N2(g) + 3H2(g) <-> 2NH3(g)

what happens if concentration of ammonia is increased?

• Favours the forward reaction

• Favours the backwards reactions