IB Chemistry HL 100113

A state of dynamic equilibrium is reached in a closed system when the rates of forward and backward reactions are equal.

Describe the characteristics of a physical and chemical system at equilibrium.

The equilibrium law describes how the equilibrium constant, $K$, can be determined from the stoichiometry of a reaction.

Deduce the equilibrium constant expression from an equation for a homogeneous reaction.

The magnitude of the equilibrium constant indicates the extent of a reaction at equilibrium and is temperature dependent.

Determine the relationships between $K$ values for reactions that are the reverse of each other at the same temperature.

Include the extent of reaction for: $K<<1$, $K<1$, $K = 1$, $K>1$, $K>>1$.

Le Châtelier’s principle enables the prediction of the qualitative effects of changes in concentration, temperature and pressure to a system at equilibrium.

Apply Le Châtelier’s principle to predict and explain responses to changes of systems at equilibrium.

Include the effects on the value of $K$ and on the equilibrium composition.

Le Châtelier’s principle can be applied to heterogeneous equilibria such as: X(g) ⇌ X(aq)

The reaction quotient, $Q$, is calculated using the equilibrium expression with nonequilibrium concentrations of reactants and products.

Calculate the reaction quotient $Q$ from the concentrations of reactants and products at a particular time, and determine the direction in which the reaction will proceed to reach equilibrium.

The equilibrium law is the basis for quantifying the composition of an equilibrium mixture.

Solve problems involving values of $K$ and initial and equilibrium concentrations of the components of an equilibrium mixture.

The approximation [reactant]_initial ≈ [reactant]_eqm when $K$ is very small should be understood.

The use of quadratic equations is not expected. Only homogeneous equilibria will be assessed.

The equilibrium constant and Gibbs energy change, $ΔG$, can both be used to measure the position of an equilibrium reaction.

Calculations using the equation $ΔG^{⦵} = -RT \ln{K}$.

The equation is given in the data booklet.