Chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction or to transform itself into other chemical substances. Forming or breaking chemical bonds involves energy. This energy can be absorbed or evolved from a chemical system.
The energy that can be released (or absorbed) by a reaction between a set of chemical substances is equal to the difference between the amount of energy of the products and the reactants. This change in energy is called the internal energy of a chemical reaction.
Since the strength of the chemical bonds is associated with the distance between the chemical species (in fact the strongest chemical bonds are those with the chemical elements involved in the closest bond), the chemical energy depends on the mutual position of the chemical bonds. particles that constitute a substance. Therefore, chemical energy is the energy stored in chemical bonds. This energy is attributable, in large part, to the sum of the potential energy of the electrostatic interactions of the charges present in the ponderable matter, plus the kinetic energy of the electrons.
If you have a "zero level" of chemical energy that is where there are no chemical bonds, the chemical energy is negative.
Resonance is a chemical-structural phenomenon that greatly influences chemical energy in the stabilizing sense. The reactivity and kinetics of the various compounds suffer from differences in chemical energy.
Chemical energy is produced in the course of the transformations that take place at the level of molecules.
Chemical energy and thermodynamics
Chemical energy has a close relationship with thermodynamics in which concepts of internal energy, enthalpy and thermodynamic processes appear.
In thermodynamic chemistry the term used for the potential energy is the chemical potential, and by the chemical transformation the Gibbs-Duhem equation is often used.
The change of internal energy of a process is equal to the change of heat if it is measured under constant volume conditions, as in a calorimeter. However, under conditions of constant pressure, the measured heat is not always equal to the internal energy change. The change of heat at constant pressure is called the enthalpy change.
Use of chemical energy in technical systems
Another useful term is the heat of combustion, which is the energy released in the combustion reaction and often applied to the study of fuels.
From a technical point of view, fuels contain chemical energy that is converted into mechanical energy through its combustion, for example, in thermal engines. The fuel allows the transformation of the chemical reaction energy of combustion directly into electrical energy or mechanical energy.
When batteries are used, chemical energy is converted directly into electrical energy through electrochemical redox reactions. An accumulator behaves similarly to a battery in the use of energy, and vice versa, can convert electrical energy into chemicals and store it.
Potential chemical energy
Potential chemical energy is a form of potential energy related to the structural arrangement of atoms or molecules. This arrangement can be the result of chemical bonds between the molecules. The chemical energy of a substance can be transformed into other forms of energy by chemical reaction.
The similar chemical potential term is used to indicate the potential of a substance to undergo a configuration change, in the form of chemical reaction, space transport, particle exchange with a reservoir.
Examples of chemical energy
Here are a few examples of chemical energy:
- Nuclear energy. In nuclear reactions of fission or fusion chemical alterations are generated in atoms that are transformed into chemical energy.
- The combustion of a fuel. We have an example of this case when burning a fuel and obtaining thermal energy in the form of heat.
- Digestion by a living organism. Food, through certain reactions in the stomach, is converted into chemical energy for the organism.
- The photosíntesi. Green plants obtain energy by transforming solar energy into chemical energy in photosynthesis, electrical energy can be converted into chemical energy through electrochemical reactions.
Last review: November 25, 2016Back