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Information about Exothermic

In thermodynamics, the word exothermic describes a process or reaction that releases energy in the form of heat. Its etymology stems from the Greek prefix ex-, meaning “outside” and the Greek word thermein, meaning “to heat”. The opposite of an exothermic process is an endothermic process, one that absorbs energy in the form of heat. The term “exothermic” was coined by Marcellin Berthelot.

The concept is frequently applied in physical sciences to e.g. chemical reactions, where chemical bond energy is converted to thermal energy (heat).

Overview

Exothermic refers to a transformation in which a system releases energy (heat) to the surroundings:

Q < 0


When the transformation occurs at constant pressure:

∆H < 0


and constant volume:

∆U < 0


In an adiabatic system (i.e. a system that does not give off heat to the surroundings), an exothermic process results in an increase in temperature.[1]

Exothermic processes

Some examples of exothermic processes are:[2]
  • Condensation of rain from water vapor
  • Combustion (for instance of a candle)
  • Mixing water and strong acids
  • Nuclear fusion

Implications for chemical reactions

Main article: exothermic reaction
Chemical exothermic reactions are generally more spontaneous than their counterparts, endothermic reactions. In a thermochemical reaction that is exothermic, the heat is placed as a product on the product's side (heat is a product of the reaction).

See also

External links

References

1. ^ Perrot, Pierre (1998). A to Z of Thermodynamics. Oxford University Press. ISBN 0-19-856552-6. 
2. ^ Exothermic - Endothermic examples
Thermodynamics (from the Greek θερμη, therme, meaning "heat" and δυναμις, dynamis, meaning "power") is a branch of physics that studies the effects of changes in temperature, pressure, and volume on
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energy (from the Greek ενεργός, energos, "active, working")[1] is a scalar physical quantity that is a property of objects and systems of objects which is conserved by nature.
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endothermic describes a process or reaction that absorbs energy in the form of heat. Its etymology stems from the Greek prefix endo-, meaning “inside” and the Greek suffix –thermic, meaning “to heat”.
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Marcellin (or Marcelin) Pierre Eugène Berthelot (October 25, 1827 - March 18, 1907) was a French chemist and politician noted in thermochemistry for the Thomsen-Berthelot principle.
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Physical science is an encompassing term for the branches of natural science, and science, that study non-living systems, in contrast to the biological sciences. However, the term "physical" creates an unintended, somewhat arbitrary distinction, since many branches of physical
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Episode no. Season 2
Episode 18
Written by Padma Atluri
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Production no. 3T5317
Original airdate June 25,2007

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In chemistry, bond energy (E) is a measure of bond strength in a chemical bond. For example the carbon-hydrogen bond energy in methane E(C–H) is the enthalpy change involved with breaking up one molecule of methane into a carbon atom and 4 hydrogen radicals
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In thermal physics, thermal energy is the energy portion of a system that increases with its temperature. In a loose sense, "thermal energy" is a term often used to describe the energy content of a system related to heating effects, e.g. temperature increase or decrease.
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Adiabatic may refer to:
  • In thermodynamics,
*Adiabatic process
*Adiabatic index
  • In quantum mechanics,
*Adiabatic process
*Adiabatic theorem
  • In electronics.

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exothermic reaction is one that releases heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation:

Overview

In an exothermic reaction, the total energy absorbed in bond breaking is less than the total energy released
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endothermic describes a process or reaction that absorbs energy in the form of heat. Its etymology stems from the Greek prefix endo-, meaning “inside” and the Greek suffix –thermic, meaning “to heat”.
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Endergonic means absorbing energy in the form of work. Its etymology stems from the suffix -ergonic as derived from the Greek root ergon meaning to work, combined with the prefix end- as derived from the Greek root en meaning put into.
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In chemical thermodynamics, an endergonic reaction (also called an unfavorable reaction or a nonspontaneous reaction) is a chemical reaction in which the standard change in free energy is positive.
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Exergonic means to release energy in the form of work. Its etymology stems from the suffix -ergonic, as derived from the Greek root ergon meaning to work, combined with the Greek prefix ex- meaning out of.
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An exergonic reaction is a chemical reaction where the variation of Gibbs free energy is negative [1]. This tells us the direction that the reaction will follow.
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