CrossRef citations to date. Altmetric. Listen. Original Articles. The relationship between kinetic and thermodynamic fragilities in metallic. The first law of thermodynamics is a version of the law of conservation of energy, adapted for .. The earlier traditional versions of the law for closed systems are nowadays often considered to be out of date. .. Equation (2) is known as the fundamental thermodynamic relation for a closed system in the energy representation. The thermodynamic free energy is a concept useful in the thermodynamics of chemical or .. the force that caused chemical reactions. The term affinity, as used in chemical relation, dates back to at least the time of Albertus Magnus in
Adiabatic processes In an adiabatic process, there is transfer of energy as work but not as heat.
For all adiabatic process that takes a system from a given initial state to a given final state, irrespective of how the work is done, the respective eventual total quantities of energy transferred as work are one and the same, determined just by the given initial and final states. The work done on the system is defined and measured by changes in mechanical or quasi-mechanical variables external to the system.
Physically, adiabatic transfer of energy as work requires the existence of adiabatic enclosures.
For instance, in Joule's experiment, the initial system is a tank of water with a paddle wheel inside. If we isolate the tank thermally, and move the paddle wheel with a pulley and a weight, we can relate the increase in temperature with the distance descended by the mass.
Next, the system is returned to its initial state, isolated again, and the same amount of work is done on the tank using different devices an electric motor, a chemical battery, a spring, In every case, the amount of work can be measured independently.
The return to the initial state is not conducted by doing adiabatic work on the system. The evidence shows that the final state of the water in particular, its temperature and volume is the same in every case. It is irrelevant if the work is electricalmechanical, chemical, Evidence of this kind shows that to increase the temperature of the water in the tank, the qualitative kind of adiabatically performed work does not matter.
No qualitative kind of adiabatic work has ever been observed to decrease the temperature of the water in the tank. A change from one state to another, for example an increase of both temperature and volume, may be conducted in several stages, for example by externally supplied electrical work on a resistor in the body, and adiabatic expansion allowing the body to do work on the surroundings. It needs to be shown that the time order of the stages, and their relative magnitudes, does not affect the amount of adiabatic work that needs to be done for the change of state.
Maxwell relations - Wikipedia
According to one respected scholar: We must therefore admit that the statement which we have enunciated here, and which is equivalent to the first law of thermodynamics, is not well founded on direct experimental evidence. For the latter, another step of evidence is needed, which may be related to the concept of reversibility, as mentioned below. In it was named as the internal energy by Helmholtz. Since it makes no reference to any quantities involved in work such as p and Vthe Helmholtz function is completely general: The Helmholtz free energy has a special theoretical importance since it is proportional to the logarithm of the partition function for the canonical ensemble in statistical mechanics.
Hence its utility to physicists ; and to gas -phase chemists and engineers, who do not want to ignore p dV work. Historically, the term 'free energy' has been used for either quantity. In physicsfree energy most often refers to the Helmholtz free energy, denoted by A or F, while in chemistryfree energy most often refers to the Gibbs free energy.
The values of the two free energies are usually quite similar and the intended free energy function is often implicit in manuscripts and presentations.
First law of thermodynamics - Wikipedia
Meaning of "free"[ edit ] The basic definition of "energy" is a measure of a body's in thermodynamics, the system's ability to cause change. For example, when a person pushes a heavy box a few meters forward, that person exerts mechanical energy, also known as work, on the box over a distance of a few meters forward.
Because the person changed the stationary position of the box, that person exerted energy on that box. The work exerted can also be called "useful energy".
- First law of thermodynamics
- Thermodynamic free energy
Because energy is neither created nor destroyed, but conserved, it is constantly being converted from one form into another. For the case of the person pushing the box, the energy in the form of internal or potential energy obtained through metabolism was converted into work in order to push the box. This energy conversion, however, is not linear. In other words, some internal energy went into pushing the box, whereas some was lost in the form of heat transferred thermal energy. For a reversible process, heat is the product of the absolute temperature T and the change in entropy S of a body entropy is a measure of disorder in a system.
In thermodynamics, this is what is known as "free energy".