Dynamic Equilibrium: A Balance in Motion
Definition
Dynamic equilibrium
Dynamic equilibrium occurs in reversible reactions within a closed system.
Definition
Reversible reaction
A reversible reaction is one in which reactants can form products (the forward reaction), while products can simultaneously revert back into reactants (the reverse reaction).
At equilibrium, the rates of the forward and reverse reactions are equal, creating a balance.
Key Characteristics of Dynamic Equilibrium:
- Constant Concentrations:
- While reactions continue to occur, the concentrations of reactants and products remain constant over time.
- However, this does not mean the concentrations are equal—only that they are unchanging.
- Dynamic Nature:
- At the molecular level, particles are continuously reacting.
- The system is not static; it is in constant motion.
- Closed System:
- The system must be closed, meaning no reactants or products can enter or leave.
- This ensures equilibrium is maintained.
- Dynamic equilibrium is a balance of reaction rates, not amounts.
- The concentrations of reactants and products may differ, but their rates of change are always equal at equilibrium.
Examples of Dynamic Equilibrium
Phase Equilibrium: Water in a Sealed Container
- Picture a sealed container with liquid water and its vapor.
- Initially, water molecules evaporate into the gas phase, increasing the concentration of water vapor.
- Over time, some vapor molecules condense back into liquid water.
- Eventually, the rate of evaporation equals the rate of condensation, and the system reaches equilibrium.
