The key difference between thermodynamic and kinetic stability is that thermodynamic stability refers to the status of products, whereas kinetic stability refers to the status of reactants.
Thermodynamic and kinetic stability are two important chemical terms describing systems with chemical reactions. Thermodynamic stability is the stability of the lowest energy state of a system while kinetic stability is the stability of the highest energy state of a system. Moreover, thermodynamic state describes an equilibrium state of a system, whereas a kinetic state describes the reactivity of a system.
CONTENTS
1. Overview and Key Difference
2. What is Thermodynamic Stability
3. What is Kinetic Stability
4. Side by Side Comparison – Thermodynamic vs Kinetic Stability in Tabular Form
5. Summary
What is Thermodynamic Stability?
Thermodynamic stability is the stability of the lowest energy state of a system. It is also known as chemical stability in general use. The lowest energy state of a system is where the optimum product yield is obtained. This means thermodynamic stability is gained when the system comes to an equilibrium state. Sometimes, this stability occurs when there is a dynamic equilibrium in which the individual atoms and molecules tend to change their form, keeping the overall change at zero point.
Figure 01: Stability of Products at Equilibrium State
The opposite of thermodynamic stability is “kinetic stability”, which describes the reactivity of a system rather than the equilibrium state of that system.
What is Kinetic Stability?
Kinetic stability is the stability of the highest energy state of a system. That means; kinetic stability occurs when there is an optimum reactant percentage in the system. This is because the reactants usually have a high energy level which makes them react with each other to convert into products that have a low energy level. Kinetic stability of a system is thus related to the reactivity of the reactants. Moreover, the reactants usually require an input of energy to move the reaction from kinetic stability to thermodynamic stability.
What is the Difference Between Thermodynamic and Kinetic Stability?
Thermodynamic and kinetic stability are important chemical terms in physical chemistry. The key difference between thermodynamic and kinetic stability is that thermodynamic stability refers to the status of products, whereas kinetic stability refers to the status of reactants. Usually, reactants of a reaction have a high energy compared to the energy level of the products. And, this is the reason why reactants tend to convert into low energy products in order to get stabilized.
Chemical reactions usually require an input of energy to move the system from kinetic stability to thermodynamic stability where optimum products are produced. Therefore, the term thermodynamic refers to the equilibrium state of a system, while the term kinetic refers to the reactivity of a system. Sometimes, thermodynamic stability gives the stability of either an equilibrium reaction or a non-equilibrium reaction.
The following table summarizes the difference between thermodynamic and kinetic stability.
Summary – Thermodynamic vs Kinetic Stability
Thermodynamic and kinetic stability are important chemical terms in physical chemistry. Thermodynamic stability is the stability of the lowest energy state of a system while kinetic stability is the stability of the highest energy state of a system. The key difference between thermodynamic and kinetic stability is that thermodynamic stability refers to the status of products, whereas kinetic stability refers to the status of reactants. Typically, a system requires some input energy in order to move the system from kinetic stability to thermodynamic stability through the reactivity of the reactants.
Reference:
1. Anthony, Day. “Kinetic Stability.” School of Crystallography, Birbeck University, 1996, Available here.
2. “Thermodynamic Stability.” an Overview | ScienceDirect Topics, Available here.
Image Courtesy:
1. “Thermodynamic stability EN” By Woudloper – Own work (CC BY-SA 3.0) via Commons Wikimedia