What are some examples of chemical energy

Chemical energy

Lexicon> letter C> chemical energy

Definition: Energy that is stored in chemical form and can be released during chemical reactions

More general terms: energy

English: chemical energy

Categories: Basic Concepts, Physical Basics

Author: Dr. RĂ¼diger Paschotta

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Original creation: 09/20/2011; last change: 01/09/2021

URL: https://www.energie-lexikon.info/chemische_energie.html

Contain many fossil or renewable energy sources chemical energy. This is usually released as heat when an (exothermic) chemical reaction takes place - usually combustion with the help of atmospheric oxygen. Since the combustion can usually be started in a targeted manner (e.g. by the burner of a boiler), the chemical energy can be called up as required. Chemical energy can usually be stored for a long time without any problems; it only has to be prevented that the chemical reaction releasing the energy takes place prematurely, or that the fuel escapes or decomposes. The usually quite high energy density is also advantageous - especially in mobile applications. Direct storage devices for electrical energy, such as capacitors, have so far been far inferior to storage devices for chemical energy in terms of energy density and storability. The same applies to rechargeable batteries, although these also store the energy in chemical rather than electrical form.

Examples of common fossil chemical energy carriers are heating oil and diesel fuel, natural gas and coal. Similar energy sources can be produced from renewable energy sources, for example biodiesel and biogas, but also synthesis gas. Chemical energy carriers can also be produced from electrical energy, in particular so-called RE gas with hydrogen and possibly methane obtained therefrom by steam reforming.

Food also contains chemical energy, and this is the energetic livelihood for all animals.

From a microscopic point of view, chemical energy is itself electrical energy - it is based entirely on electrical interactions at the molecular level. Nevertheless, it is usually not referred to as electrical energy, as it is usually completely different in terms of use. There are, however electrochemical Apparatus such as B. Batteries, where chemical energy can be taken or supplied directly as electrical energy - usually with a very high degree of efficiency, without any combustion taking place.

Enthalpy of combustion

The energy released during combustion (or another exothermic chemical reaction) is the difference between the energies contained in the starting and end products. A lot of energy is released when energy-rich products (fuels) are converted into low-energy substances such as B. water and carbon dioxide are converted.

Strictly speaking, the amount of heat released is also called Enthalpy of reaction denotes, not necessarily identical to the mentioned difference in energies, since the volume of the substances can also change and changes in volume under the influence of atmospheric pressure mean an additional supply or removal of energy. If z. B. hydrogen reacts with oxygen, the resulting water vapor has a smaller volume than the starting materials. The atmospheric pressure then means that volume work is added to the reaction energy, i.e. a little more heat is released. In other cases, e.g. B. in the combustion of hydrocarbons, this can be the other way around.

Conversion of chemical energy into other forms of energy

Chemical energy storage

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See also: energy, enthalpy, binding energy, chemical energy storage, energy carrier, fossil energy carrier, fuel, calorific value, calorific value, fuel cell
as well as other articles in the categories basic concepts, physical fundamentals