# application of gibbs free energy in daily life

Related questions Can gibbs free energy be negative? How do enzymes affect gibbs free energy? How is Gibbs Free Energy calculated? How is gibbs free energy related to enthalpy and entropy? Changes in free energy and the reaction quotient. Standard change in free energy and the equilibrium constant. Note: Conjugate variables in italics. Work Heat. Material properties.

Carnot's theorem Clausius theorem Fundamental relation Ideal gas law. Free energy Free entropy. History Culture. History General Entropy Gas laws. Entropy and time Entropy and life Brownian ratchet Maxwell's demon Heat death paradox Loschmidt's paradox Synergetics.

Caloric theory Theory of heat. Heat ". Thermodynamics Heat engines. See also: Thermodynamic free energy. This section may be confusing or unclear to readers. In particular, the physical situation is not explained. Also, the circle notation is not well explained even in the one case where it is attempted. It's just bare equations. Please help us clarify the section.

There might be a discussion about this on the talk page. March Learn how and when to remove this template message. A to Z of Thermodynamics. The useful work arises only due to the heat exchange with a thermal basin in the process, described by the scheme I. However, using VHEB as an example, It is clear that the energy of chemical reactions is first converted into the thermal energy of thermostat environment and then the thermal energy is extracted from the thermostat and transformed into work by means of special devices.

It is assumed then that in galvanic cells, useful work is produced via the mechanism similar to the VHEB one [ 12 , 13 ]. The electric work of a galvanic cell results from the electrodes discharged. Electric charging of electrodes is caused by chemical reactions in electrodes. The mechanism of electric energy production in galvanic cells will be solved by analyzing the behavior of one ion.

But it does not denote that thermodynamics will be applied to a real single ion: thermodynamic parameters of one ion imply the averaged parameters of many ions. Let the cell with an open, external circuit be in equilibrium. Close now the external circuit for the moment and two electrons will transfer from the zinc to the copper electrode.

The balance of the cell is distorted. Consider now the establishment of equilibrium on the zinc electrode Fig 3. To this end, the zinc ion must leave a metallic plate and escape into the bulk. The dissolving of zinc ions is described by the change in a Gibbs function. The ion penetrates further into solution with execution of the work w 1 g in the electric field. The work described in equation 17 , is the electric work spent to charge an electrode. It is performed at the extraction of the thermal energy of solution due to the absence of other energy sources in the system.

Since in equilibrium, the chemical potential of ions in solution equals the chemical potential of metal, it is possible to derive the equation for electrochemical equilibrium. The latter is the potential for a half-cell. Thus, the approach, based on the consideration of the behavior of one ion, provides a common expression for electrode potential.

The change in electrode enthalpy involves dissolution enthalpy and thermal energy consumption upon ion transport into solution. The equation for dissolution enthalpy is readily obtained from eq. As follows from eq.

Therefore, studying either release or absorption of heat on a separate electrode, one may calculate the change in entropy due to the escape of the ions of the same type into the bulk. A corresponding expression for the second electrode is of the same form but index "1" should be substituted by index "2":.

In the operation of the galvanic cell, the processes on the second electrode are oppositely directed which should be taken into account in consideration of the thermodynamic cell parameters. Equations 20 and 26 allow to get the Nernst equation for the potential of the cell [ 3 ].

The electric work of the galvanic cell w el results from the transformation of the potential energy of the charged electrodes into electric energy. The potential energy arises from the thermal energy of both of the electrodes upon ions transport into solution and equals. The sum of eqs. Thus, the approach, based on the analysis of the behavior of one ion gives the same results as the present-day theory. The electric energy of the galvanic cell arises according to the scheme:.

Thus, in various systems with uniform temperature, useful work is produced by the same mechanism through the exchange of thermal energy with thermostat environment.

No direct conversion of chemical energy into useful work is observed. Unfortunately, in the galvanic cell, the processes of heat release and useful work production cannot be spatially separated, because both of them occur in a double layer. Therefore, galvanic cells are unpromising in production of a double amount of energy.

Consider now a concentration cell, consisting of two electrodes, e. Standard changes in the Gibbs function, enthalpy, and entropy for the concentration cell tend to zero due to the same chemical nature of both of the electrodes. Examination of the Ellingham diagram shown above illustrates why the metals known to the ancients were mainly those such as copper and lead, which can be obtained by smelting at the relatively low temperatures that were obtainable by the methods available at the time in which a charcoal fire supplied both the heat and the carbon.

Thus the bronze age preceded the iron age ; the latter had to await the development of technology capable of producing higher temperatures, such as the blast furnace. Smelting of aluminum oxide by carbon requires temperatures too high to be practical; commercial production of aluminum is accomplished by electrolysis of the molten ore.

Many of the reactions that take place in living organisms require a source of free energy to drive them. The immediate source of this energy in heterotrophic organisms, which include animals, fungi, and most bacteria, is the sugar glucose. Oxidation of glucose to carbon dioxide and water is accompanied by a large negative free energy change.

Effective utilization of this free energy requires a means of capturing it from the glucose and then releasing it in small amounts when and where it is needed. The complete breakdown of one molecule of glucose is coupled with the production of 38 molecules of ATP according to the overall reaction. The rest is liberated as heat. Where does the glucose come from? Animals obtain this food by eating plants or other animals.

Ultimately, all food comes from plants, most of which are able to make their own glucose from CO 2 and H 2 O through the process of photosynthesis. The photosynthesis-respiration free energy cycle. This describes aerobic respiration , which evolved after the development of photosynthetic life on Earth began to raise the concentration of atmospheric oxygen. Oxygen is a poison to most life processes at the cellular level, and it is believed that aerobic respiration developed as a means to protect organisms from this peril.

The function of oxygen in respiration is to serve as an acceptor of the electrons that glucose loses when it undergoes oxidation. Other electron acceptors can fulfill the same function when oxygen is not available, but none yields nearly as much free energy. For example, if oxygen cannot be supplied to mammalian muscle cells as rapidly as it is needed, they switch over to an anaerobic process yielding lactic acid instead of CO 2 :.

Respiration and many other metabolic processes involve electron-transfer reactions; see below for more on this. In , Gurney showed how this idea could be made even more useful by placing acid-base conjugate pairs on a proton-free energy scale. The proton-free energy concept is commonly employed in aquatic environmental chemistry in which multiple acid-base systems must be dealt with on a semi-quantitative bases. It is, however, admirably adapted to any presentation of acid-base chemistry, even at the first-year college level, and it seems a shame that it never seems to have made its way into the ordinary curriculum.

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