Helmholtz Free Energy

The Helmholtz free energy is a thermodynamic potential in thermodynamics that estimates the “useful” work that a closed thermodynamic system may produce at a constant temperature and volume. The negative of the difference in Helmholtz energy for such a system is equal to the maximum amount of work that can be extracted from a thermodynamic process with constant temperature and volume. It is minimized at equilibrium under certain conditions. Hermann von Helmholtz created the Helmholtz free energy, which is generally represented by the letter A.

The Helmholtz energy is represented as A = U – TS, where A is the Helmholtz free energy (SI: joules, CGS: ergs).

 U represents the system’s internal energy (SI: joules, CGS: ergs), T represents the absolute temperature (kelvins), and S represents the entropy (SI: joules per kelvin, CGS: ergs per kelvin). The negative Legendre transform of the basic relation in the energy representation, U, with regard to the entropy, S, is the Helmholtz energy U(S, V, N). 

T, V, and N are A’s natural variables.

Absolute Temperature:

Temperature measured on the Kelvin scale, where zero represents absolute zero, is referred to as absolute temperature. The zero point is the temperature at which matter particles have the least amount of motion and cannot get any colder (minimum energy). 

A thermodynamic temperature reading is not preceded by a degree symbol because it is “absolute.”

Despite being based on the Kelvin scale, the Celsius scale does not measure absolute temperature since its units are not relative to absolute zero. Another absolute temperature scale is the Rankine scale, which has the same degree interval as the Fahrenheit system. Fahrenheit, like Celsius, is not an absolute scale.

Spontaneity:

The total energy in an isolated system always remains constant, according to the First Law of Thermodynamics. We can understand the relationship between the system’s work and the heat absorbed without disturbing the direction of heat flow with the help of the first law of thermodynamics. 

All naturally occurring processes normally proceed in only one way. 

Define spontaneity and the factors influencing spontaneity direction.

A spontaneous process is an irreversible process. However, by using some external agents,you may  reverse the process  sometimes. Entropy is the  measurement of the quantity of unpredictability in any system.

How to Predict a Reaction’s Spontaneity:

In general, total entropy change is the most important parameter for describing the spontaneity of any process. We may claim there is a change in enthalpy coupled with a change in entropy because most chemical reactions are either closed or open systems.

We can say that entropy change alone cannot be accountable for the spontaneity of such a process because it affects molecular movements and enhances or decreases randomness. As a result, we utilize the Gibbs energy change to explain the spontaneity of a process.

Equilibrium and spontaneity criteria:

Three criteria have been found to determine whether a reaction will occur spontaneously:

Suniv > 0, Gsys 0 and the relative magnitude of the reaction quotient Q versus the equilibrium constant K. (For additional details on the reaction quotient and the equilibrium constant, see Reaction Quotient and Equilibrium Constant.) 

Remember that if Q K, the reaction proceeds spontaneously to the right as given, resulting in net reactant-to-product conversion.

If Q > K, on the other hand, the reaction proceeds spontaneously to the left as specified, resulting in net product to reactant conversion. If Q = K, the system is at equilibrium, and there is no net response. 

These criteria and their respective values for spontaneous, nonspontaneous, and equilibrium processes are summarised in “Criteria for the Spontaneity of a Process as Written.” Because all three criteria are evaluating the same thing process spontaneity,it would be quite remarkable if they were unrelated. “Free Energy” depicted the interaction between Suniv and Gsys.

The Equilibrium and Free Energy Constant:

We should be able to express K in terms of G° and vice versa since H° and S° control the magnitude of G° , and because K is the measure of the ratio of product to reactant concentrations.

 G is equal to the maximum amount of work a system may produce on its surroundings while undergoing a spontaneous change, as you taught in “Free Energy.” 

We can predict the change in free energy in terms of  entropy, volume, pressure and temperature for a reversible process that does not include external work, removing H from the equation for G.

Conclusion:

Helmholtz Free Energy in Practice:The Helmholtz function, which is a sum of ideal gas and residual components, is used to represent pure fluids with high accuracy (such as industrial refrigerants).

Experts utilise an artificial neural network called an auto-encoder to encode data efficiently. In addition, the specialists here employ Helmholtz energy to calculate the total cost of the code and the reconstructed code.