The Relationship Between Thermodynamics and Chemical Equilibrium

Thermodynamics is an area of physics that deals with heat, work, and internal energy processes. Thermodynamics is concerned with the system’s macroscopic rather than microscopic behaviour. Before discussing the definitions of thermal equilibrium and chemical equilibrium, let us understand thermodynamics. Thermodynamic rules govern the interactions of heat with mechanical, electrical, and other types of energy or work. The principles apply only to systems in thermal equilibrium, not to systems in the process of fast change or with intricate transition states. A reversible system is always nearly in balance.

Thermodynamic Processes

A thermodynamic process or a thermodynamic change is a process in which one or more parameters of a thermodynamic system change. There are various types of thermodynamic processes, such as:

• Isothermal process: An isothermal change is defined as a change in pressure and volume that occurs at a constant temperature. It should be emphasised that the overall amount of heat in the system does not remain constant during such a change.
• Isobaric process: An isobaric process is one where changes in volume and temperature of gas occur under constant pressure.
• Isochoric process: Isochoric processes are those in which variations in pressure and temperature occur while the system’s volume remains constant.
• Adiabatic process: An adiabatic change is defined as a change in pressure, volume, and temperature that occurs without any heat entering or exiting the system.
• Quasi-static process: A quasi-static process is one in which changes in any of the parameters occur at such a slow rate that the values of pressure, volume, and temperature can be assumed to be nearly constant.
• Cyclic process: A cyclic process refers to a system where the parameters revert to their initial values.
• Free expansion: Free expansion is defined as an expansion in which no external effort is performed, and the total internal energy of the system remains constant.

The Concept of Chemical Equilibrium

Chemical equilibrium occurs when the amounts of reactants and products do not change in a reversible chemical reaction. A reversible chemical reaction occurs when products get attached to the legal reactants the moment they are produced. Chemical equilibriums occur when forward and reverse reaction rates in a chemical reaction are equal. As a result of this equilibrium, the concentrations of the reactants and products remain unchanged. However, the fact that concentrations are not changing does not rule out the possibility of chemical interactions. Chemical equilibrium is a dynamic condition in which reactants are constantly changed into products, but at the precise rate that products are turned back into reactant molecules. The effect is similar to a bridge connecting two cities, with the rate of cars crossing the bridge in each direction being exactly equal. As a result, there is no change in the net number of cars on either side of the bridge.

Types of Chemical Equilibriums

The two different types of chemical equilibriums are homogeneous and heterogeneous equilibriums.

• Homogeneous equilibrium – 

The term homogeneous is derived from the Greek terms homos, which means the same, and genos, which means race or type. All species present are in the same state in a homogeneous equilibrium.

• Heterogeneous equilibrium – 

The term heterogeneous is derived from the term heteros, which means other. The species present in a heterogeneous equilibrium are in a variety of states. The breakdown of solid calcium carbonate is one example. It decomposes into another solid, calcium oxide, and a gas, carbon dioxide:

Conclusion 

The equilibrium state of a system is a thermodynamic state that is constant in time. This has nothing to do with any external processes. There are various types of equilibria. Any adjacent states of the system are less steady if the equilibrium is stable. External work would be required to shift from the equilibrium state to these nearby ones. It is also common for steady equilibrium to be addressed from two different angles. Thermal equilibrium and chemical equilibrium, however, are limited to steady equilibria, often known as chemical equilibria.