Chemical Equilibrium

What is the Equilibrium Concept?

Its the concept of the rate of the forward reaction being equal to the rate of the reverse reaction.

What is the equilibrium constant?

It is a numerical value that represents the ratio of products to reactants at equilibrium. The k expression is only determined by stoichiometry of the reaction not the mechanism.

At equilibrium, is K independent or dependent of the initial reactant and product amounts?

It is independent

In heterogenous mixtures, do we include pure solids and liquids in the K expression?

No

What do we use to find the K of the reverse reaction from the forward reaction?

1/ (K forward reaction)

What expression do we use to find the K of a reaction that is a multiple of a reaction, i.e. n x Reaction?

K^n

What expression do we use to find the net K?

K1 x K2

What is the reaction quotient?

It is like the K constant in that it is a numerical value for the ratio of reactants to products, but just not at equilibrium. It’s at any point in the reaction

Why do we compare the reaction quotient to the equilibrium constant?

It helps us to determine whether a reaction is at equilibrium or not. If it isn’t, it tells us in which direction the reaction must proceed in order to reach equilibrium.

what does “Q<K” tell us?

It tells us that a higher [products] required for equilibrium

What does “Q>K” tell us?

It tells us that a higher [reactants] is required for equilibrium

What does “Q=K” tell us?

It tells us the system is at equilibrium

What is Le Chateliers principle?

If a system is at equilibrium and it is disturbed in temperature, pressure or component concentration. The system will shift its equilibrium position to counteract the change and restore equilibrium.

Out of changes to volume/pressure, temperature and component concentration, which one results in a change to the equilibrium constant?

A change in temperature

What does a catalyst do?

A catalyst makes no changes to the equilibrium concentrations of reaction components or the K value. It lowers the activation energy so that the reaction reaches equilibrium faster and it increases the reaction rate.