Definition - What does Equilibrium Reaction mean?
An equilibrium reaction is a chemical reaction between the reactants that stays in a stable state before and after the completion of the reaction (i.e., in a thermodynamic equilibrium state). A reaction is said to be in a thermodynamic equilibrium state when it satisfies all three types of equilibrium:
- Thermal equilibrium
- Chemical equilibrium
- Mechanical equilibrium
The product obtained from an equilibrium reaction also remains in equilibrium with the reactants.
Corrosionpedia explains Equilibrium Reaction
An equilibrium reaction abides by the so-called "minus first" or "zeroth" law of thermodynamics. Per this law of thermodynamics, if the first object is in equilibrium with the second object and the second object is in equilibrium with the third object, then the first and third objects will also be in equilibrium. An equilibrium reaction satisfies thermal, chemical and mechanical equilibrium states.
- Thermal equilibrium is a state in which two substances or objects in physical contact have no difference in their temperatures (i.e., either the objects have the same temperature or both objects are connected by a permeable barrier that does not allow the transfer of heat between the two objects). Thermal equilibrium is mainly associated with the laws of thermodynamics in physics and mechanics.
- Chemical equilibrium is a state where there is no chemical reaction occurring between the various objects, or any transfer of matter from one part of the system to another part due to any kind of diffusion. Thus, during a chemical equilibrium the chemical potential of the various systems remains the same.
- Mechanical equilibrium is a state where there are no unbalanced forces acting within the system or between the system and its surroundings. Thus, the pressure throughout the system remains the same or constant.