Chemical Equilibrium Flashcards

Flashcards covering key vocabulary and concepts related to chemical equilibrium.

Reversible Reaction

A reaction where the entire amount of reactants is not converted into products.

Irreversible Reaction

A reaction where the entire amount of reactants is converted into products.

Characteristics of Reversible Reactions

Can be started from either side, never complete, tend to attain equilibrium (ΔG = 0).

Characteristics of Irreversible Reactions

Proceed only in one direction, can proceed to completion, ΔG < 0.

Equilibrium State

The state at which the concentration of reactants and products do not change with time; concentrations become constant.

Law of Mass Action

The rate of a chemical reaction is directly proportional to the product of the molar concentrations of the reactants at a constant temperature.

Active Mass

Molar concentration, expressed by enclosing the symbols of formulae of the substance in square brackets (e.g., [A]).

Equilibrium Constant (Kc)

Ratio of rate constants (kf/kb) or ratio of product of concentrations of products to reactants at equilibrium.

Kp

Equilibrium constant in terms of partial pressures.

Kx

Equilibrium constant in terms of mole fraction.

Relationship between Kp and Kc

Kp = Kc(RT)^Δn

Characteristics of Equilibrium Constant

Independent of original concentrations, definite value at a particular temperature, varies with temperature, K' = 1/K, tells extent of reaction, independent of catalyst.

Concentration Quotient (Q)

Ratio of the product of concentrations of products to that of reactants at any point in time. At equilibrium Q = K.

Homogeneous Equilibrium

Equilibrium reactions in which all reactants and products are in the same phase.

Heterogeneous Equilibrium

Equilibrium reactions in which reactants and products are present in different phases.

Relationship between ΔG° and K

ΔG° = -2.303 RT log K

Le Chatelier's Principle

If a system at equilibrium is subjected to a change in conditions, the system will adjust itself to counteract the change and restore a new equilibrium.

Application of Le Chatelier's Principle

Predicting the shift in equilibrium due to changes in concentration, pressure, or temperature: exothermic reactions by increasing temperature and endothermic reactions at low temperatures, or vice versa.