Homogeneous equilibrium

Definition

Homogeneous equilibrium refers to a state of balance in a chemical reaction where all reactants and products are in the same phase, such as all gases or all liquids. This type of equilibrium is significant because it allows for the application of equilibrium constants that are specific to reactions occurring in a single phase, making it easier to analyze the concentrations of the substances involved.

5 Must Know Facts For Your Next Test

1. In homogeneous equilibrium, all species are in the same physical state, allowing for straightforward calculations of concentration changes.
2. The equilibrium constant expression for a homogeneous reaction only includes gaseous and aqueous species, as solids and liquids do not appear in the expression.
3. Homogeneous equilibria can be affected by changes in concentration, temperature, and pressure, leading to shifts in the position of equilibrium.
4. The value of the equilibrium constant (K) is temperature-dependent; thus, changing the temperature will alter K and shift the equilibrium position.
5. Reactions at homogeneous equilibrium can be reversible, meaning that both the forward and reverse reactions occur simultaneously until balance is achieved.

Review Questions

• How does homogeneous equilibrium differ from heterogeneous equilibrium, and why is this distinction important?
  • Homogeneous equilibrium occurs when all reactants and products are in the same phase, while heterogeneous equilibrium involves different phases. This distinction is important because it affects how we write equilibrium constant expressions; in homogeneous equilibria, only concentrations of gaseous and aqueous substances are included. Understanding this difference helps predict how changes in conditions will affect the system's behavior.
• Discuss how Le Chatelier's Principle applies to homogeneous equilibria and provide an example.
  • Le Chatelier's Principle states that if an external change is applied to a system at equilibrium, the system will adjust to counteract that change. In homogeneous equilibria, if you increase the concentration of a reactant, for example, the system will shift towards producing more products to re-establish equilibrium. An example is increasing reactant concentration in a gas-phase reaction, which will drive the reaction towards producing more gaseous products until a new balance is achieved.
• Evaluate the impact of temperature changes on the position of homogeneous equilibria and relate this to reaction spontaneity.
  • Changing temperature affects homogeneous equilibria by altering the value of the equilibrium constant (K). For endothermic reactions, increasing temperature raises K, favoring product formation and driving the reaction forward. Conversely, for exothermic reactions, increased temperature decreases K, pushing the reaction toward reactants. Understanding this relationship helps evaluate reaction spontaneity since spontaneity is determined by changes in free energy, which is influenced by both temperature and K.

Related terms

Equilibrium Constant (K): A numerical value that expresses the ratio of concentrations of products to reactants at equilibrium for a given reaction at a specific temperature.

Le Chatelier's Principle:

A principle stating that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change and restore balance.

Chemical Reaction Quotient (Q): A measure of the relative amounts of reactants and products present during a reaction at any point in time, which can be compared to the equilibrium constant to determine the direction of change.