Chemical Equilibrium Basics

Chemical Equilibrium

• The state in which both reactants and products are present in concentrations that have no further tendency to change with time is called chemical equilibrium.
• When the reaction rates of the forward and backward reactions are equal, the system is in chemical equilibrium.
• In 1803, Berthollet discovered that the reaction between calcium hydroxide and carbon dioxide was reversible, leading to the development of the concept of chemical equilibrium.

Equilibrium Position

• If a reaction mixture is described as being in equilibrium position 'far to the right', it indicates that the reaction has proceeded mostly to the products side.

Necessary Condition

• The necessary condition for chemical equilibrium is that the rates of forward and backward reactions are equal.

Law of Mass Action

• The law of mass action is valid for reactions in equilibrium.
• The law of mass action relates to the stoichiometry of reactions, stating that the rate of a reaction is proportional to the concentrations of the reactants.

Effect of Catalyst

• Adding a catalyst does not affect the equilibrium constant.

Le Châtelier's Principle

• Le Châtelier's principle predicts that when equilibrium conditions change, the system will adjust to counteract the change and re-establish equilibrium.

Dynamic Equilibrium

• In dynamic equilibrium, the forward and backward reactions occur at the same rate, resulting in no net change in the concentrations of reactants and products at the molecular level.