In thermodynamics, the Helmholtz free energy is a thermodynamic potential that estimates the useful work available from a closed thermodynamic system at a constant temperature. Let’s look into Helmholtz Energy and how it differs from Gibbs Energy.
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What is Helmholtz free energy?
Helmholtz free energy is a concept in thermodynamics where the work of a closed system with constant temperature and volume is measured using thermodynamic potential. It may be described as the following equation:
- F = U -TS
- Where,
- F = Helmholtz free energy in Joules
- U = Internal energy of the system in Joules
- T = Absolute temperature of the surroundings in Kelvin
- S = Entropy of the system in joules per Kelvin
Derivation:
The Helmholtz equation is derived using the law of thermodynamics, so according to 1st law of the thermodynamics
- πΉQ = πΉW + dU
If the 1st law of thermodynamics is applied to closed systems,
- For the close system
- πΉQ = TdS
- πΉW = PdV
- ggg
- dU = d(TS) – SdT – PdV
- Note: d(TS) = SdT – TdS
- dU – d(TS) = – (SdT + PdV)
- dF = – (SdT + PdV)
Application of Helmholtz Free Energy
In equation of state:
The Helmholtz function is used to describe pure fluids with great precision as the sum of an ideal gas and residual components, such as industrial refrigerants.
In auto-encoder:
An artificial neural network called an auto-encoder is used to encode data efficiently. The total cost of the original code and the rebuilt code is calculated here using Helmholtz energy.
Related Articles:
What is Helmholtz Function?
Helmholtz function is a thermodynamic function which is defined as the decrease in the function and is equal to the maximum amount of work which is available during reversible isothermal process.
Difference Between Helmholtz free energy and Gibbs free energy
| Helmholtz free energy. | Gibbs free energy |
| Β Useful work that is obtained from a particular system. | Maximum reversible work that is obtained from a particular system. |
| It is the energy required to create a system at constant temperature and volume. | It is the energy required to create a system at constant pressure and temperature. |
| Helmholtz free energy finds less application as the volume of the system should be constant. | Gibbs free energy finds more application as the pressure of the system is constant. |
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Frequently Asked Questions β FAQs
Define Helmholtz free energy.
Define Gibbs free energy.
Why does an auto-encoder use Helmholtz energy?
Give the formula for calculating Helmholtz free energy.
Where,
S β entropy of the system
F β Helmholtz free energy
U β the internal energy of the system
T β absolute temperature of the surroundings
True or false: The energy needed to establish a system with constant volume and temperature is called the Helmholtz free energy.
Learn about the first law of thermodynamics in detail.
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