Free energy

Free energy refers to the energy in a physical system that can be converted to do work, in particular, the energy that is available after the system has reached equilibrium. The concept is central to thermodynamics, chemistry, and physics, and is used in a variety of scientific and engineering calculations.

Overview

In thermodynamics, the term "free energy" is used to describe the amount of energy that can be extracted from a system to perform work at a constant temperature and pressure. This is often referred to as the Gibbs free energy, named after Josiah Willard Gibbs, who introduced the concept in the 19th century.

In a similar vein, the Helmholtz free energy is the energy that can be converted into work at a constant temperature and volume. It is named after Hermann von Helmholtz, who developed the concept independently of Gibbs.

Free Energy in Thermodynamics

In thermodynamics, the concept of free energy is used to determine the direction of spontaneous processes. A process will occur spontaneously if it leads to a decrease in the system's free energy. This principle, known as the second law of thermodynamics, is fundamental to understanding and predicting the behavior of physical and chemical systems.

Free Energy in Chemistry

In chemistry, the concept of free energy is used to predict the feasibility of chemical reactions. The change in Gibbs free energy (ΔG) during a reaction determines whether the reaction will occur spontaneously. If ΔG is negative, the reaction will occur spontaneously; if it is positive, the reaction will not occur spontaneously.

Free Energy in Physics

In physics, the concept of free energy is used in the study of phase transitions, such as the transition from a liquid to a gas or from a solid to a liquid. The free energy of a system can also be used to calculate the equilibrium constant for a reaction, which is a measure of the extent to which a reaction will proceed.

See Also

• Thermodynamics
• Chemistry
• Physics
• Gibbs free energy
• Helmholtz free energy
• Second law of thermodynamics