Difference Between Thermodynamics And Kinetics (With Table)

Science is broadly divided into three fields – physics, chemistry, and biology. The first branch, that is physics, is further subdivided into many parts like mechanical, radioactive, particle, wave, etc. Among the most significant fields of work, thermodynamics and kinetics are crucial to the completion of any degree. These two fields have a wider scope and are not just limited to this interdisciplinary approach.

Thermodynamics vs Kinetics

The main difference between Thermodynamics and Kinetics is that the former is based on the occurrence while the latter is based on the speed with which a particular chemical reaction or process might proceed. Both are based on mathematical facts and scientific guesses. Catalysts, inhibitors, etc are used to control the rate of the reaction.

Thermodynamics is defined as the study of the spontaneity of a reaction. It works on the principle of guesswork since the expected fate of the reactants is the focus of this discipline.

Kinetics is defined as the study of the rate of a reaction. Molecules, as well as other materials, can be considered for this conversion. Kinetics deals more with speed than with the possibility of a reaction.

Comparison Table Between Thermodynamics And Kinetics

Parameters of ComparisonThermodynamicsKinetics
DefinitionIt is the study of the relationship between thermal energy and other interconvertible forms. It is the study of the movement of a chemical reaction under controlled atmospheric conditions when suitable force is applied.
Main TheoremThermodynamics is mainly characterized by the concept of free energy change, also known as Gibbs’ free energy. Kinetics relies on the activation energy required by the reactants in overcoming the nearest energy barrier so that the reaction can take place speedily.
Scope of ApplicationIt applies only in the case of stability. It applies only in the case of transitional phases.
The Most Important ParameterThe driving force of a particular reaction is the most important determining factor of thermodynamics. The overcoming of existing energy barriers is considered to be the most essential aspect of kinetics.
Problems SolvedSolves issues related to the occurrence of a reaction. Solves issues related to the speed with which a probable reaction would occur.

What is Thermodynamics?

Thermodynamics answers the questions like whether a reaction will take place or not. The probability is guessed by using the laws of thermodynamics in the pure state. There are numerous constant factors too, which affect the spontaneity of the particular process. Moreover, the products should have high latent stability than the individual reactants to favor the rightward movement of a particular reaction.

Thermodynamics relies on the decrease in free energy. It is commonly held that free energy can exist in three states – positive, negative, and zero. As far as spontaneous reactions concerning thermodynamics is concerned, the negative value of free energy is a crucial aspect. The Arrhenius equation also plays an important role since temperature variations have a direct relation with thermodynamic processes.

Thermodynamics also maintains equilibrium. It can further be studied as stable and metastable. When states of matter transform into other interconvertible forms by controlling certain external factors, a set amount of energy is required to push the reactive material in the right direction. It is also known as the driving force which is used to determine the minimum activation energy. The essence of thermodynamics in chemical reactions is high due to the accurate guesses on these terms.

What is Kinetics?

The time in which the reactant will be converted into the desired products is the main contention while referring to the kinetic model. There is no discussion regarding the final stage or the fate of the products after they are left at optimum conditions. In other words, the theorem is kinetics is more dynamic than thermodynamics, irrespective of the etymology.

Kinetics usually deals with rate determination, though no external force can be used to influence the aforementioned rate. The calculations help the theorist analyze the reactivity of two or more substances which further enhances research work. The particular state required for studying kinetics accurately is the transition state. In other words, the systems need not be at equilibrium but in a state of constant movement between nonequilibrium and equilibrium (or vice versa).

Kinetics needs the time gap between two modes of conversion. There are energy barriers to be overcome by the reactants to reach the final state of equilibrium. The same is the case with the conversion of products back into reactants, as per the need of the chemical process. At times, kinetics also helps in determining the changes brought about in material phases too.

Main Differences Between Thermodynamics And Kinetics

  1. Thermodynamics deals with spontaneity, that is, the probability of occurence of chemical processes. On the other hand, the principles of kinetics help in evaluating the speed at which one the reactants will convert into the products.
  2. The theorem which adds reliability to the principles of thermoynamics is free energy while kinetics is ruled mostly by activation energy.
  3. The scope of application is limited to the state of equilibrium or stability for thermodynamic processes. Kinetics can function only when the material is in transitional phase.
  4. One of the most essential parameters of thermodynamics is the latent driving force while kinetics focuses majorly on the time taken in overcoming the energy barriers.
  5. The major problems solved by the theorems of thermodynamics include the occurence or non-occurence of a particular reaction. Kinetics lays emphasis on the time elapsed between two interconvertible phases.

Conclusion

Various processes differ based on the mode of conduction, characteristics, final results, and many other parameters. As far as thermodynamics and kinetics are concerned, their variations are much more intricate thanks to the inclusivity. In other words, thermodynamics and kinetics are different yet related. The interrelationship is considered to be chemical.

Scientists mainly focus on the common points for fuelling reactions. Academic proofs of both the processed do not matter as much as the mathematical calculations. The associated laws and theorems can be considered for the process of solving numerical simultaneously. Graphical methods are also applicable in most cases.

References

  1. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.90.055701
  2. https://www.cambridge.org/core/journals/mrs-bulletin/article/thermodynamics-and-kinetics-of-bulk-metallic-glass/546246550826033673E52F0728A94052
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