Equilibria

Question 1

What is dynamic equilibrium?

Answer 1

when the rates of a forward and reverse reaction are equal.

Question 2

What is a closed system?

Answer 2

when the reaction is carried out in a sealed container, so no reactants or products are lost.

Question 3

Describe the concentrations of reactants and products at equilibrium

Answer 3

At equilibrium the concentrations of reactants and products are constant but not necessarily equal.

Question 4

Describe why chemists move the position of equilibrium

Answer 4

Chemists in industry often move the position of equilibrium to favour the products and maximise their profits.

Question 5

How does changing temperature affect equilibrium?

Answer 5

• Increasing the temperature favours the endothermic reaction.
• Decreasing the temperature favours exothermic reaction.
• LExHEn

Question 6

How does changing pressure affect equilibrium?

Answer 6

• Changing pressure ONLY affects substances that are in a gaseous state.
• Increasing the pressure favours the side with less moles of gas.
• Decreasing the pressure favours the side with more moles of gas.

Question 7

How does adding or removing reactants or products affect equilibrium?

Answer 7

• Adding a reactant (or removing a product) – will shift equilibrium to the right (this is to compensate the gain/loss).
• Adding product (or removing a reactant) – shift the equilibrium to the left.
• Neutralisation reactants can affect equilibrium if the equation contains acidic hydrogen (H+)ions or alkili hydroxide (OH-) ions.
• Adding NaOH will add hydroxide ions which can react with the H+ to form water (therefore adding a reactant).

Question 8

State the effect catalysts have on equilibrium.

Answer 8

• Catalyst have no effect on equilibrium position.
• They will allow equilibrium to be reached quicker and at a lower temperature.