Reversible reactions and dynamic equilibrium

What is a reversable reaction?

One where the products of the reaction can react to produce the original reactants

How can he direction of reversible reactions can be changed?

By changing the conditions.

What does it mean if a reversible reaction is exothermic in one direction?

It is endothermic in the opposite direction. The same amount of energy is transferred in each case.

What happens when a reversible reaction occurs in apparatus which prevents the escape of reactants and products?

Equilibrium is reached when the forward and reverse reactions occur at exactly the same rate.

What do the relative amounts of all the reactants and products at equilibrium depend on?

The conditions of the reaction.

What happens if a system is at equilibrium and a change is made to any of the conditions?

The system responds to counteract the change.

How can the effects of changing conditions on a system at equilibrium be predicted

Using Le Chatelier’s Principle.

What happens if the concentration of one of the reactants or products is changed?

The system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again.

What happens if the concentration of a reactant is increased?

More products will be formed until equilibrium is reached again.

What happens if the concentration of a product is decreased?

More reactants will react until equilibrium is reached again.

What happens if the temperature of a system at equilibrium is increased?

• The relative amount of products at equilibrium increases for an endothermic reaction.

• The relative amount of products at equilibrium decreases for an exothermic reaction.

What happens if the temperature of a system at equilibrium is decreased?

• The relative amount of products at equilibrium decreases for an endothermic reaction.

• The relative amount of products at equilibrium increases for an exothermic reaction.

For gaseous reactions at equilibrium, what does an increase in pressure cause?

The equilibrium position to shift towards the side with the smaller number of molecules as shown by the symbol equation for that reaction.

For gaseous reactions at equilibrium, what does a decrease in pressure cause?

The equilibrium position to shift towards the side with the larger number of molecules as shown by the symbol equation for that reaction.