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Endothermic
 
 
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In thermodynamics
Thermodynamics

In physics, thermodynamics is the study of the conversion of heat energy into different forms of energy ; different energy conversions into heat energy; and its relation to macroscopic variables such as temperature, pressure, and volume....
, the word endothermic "within-heating" describes a process or reaction that absorbs energy in the form of heat
Heat

In physics and thermodynamics, heat is any transfer of energy from one body or thermodynamic system to another due to a difference in temperature....
. Its etymology stems from the Greek prefix endo-, meaning “inside” and the Greek suffix –thermic, meaning “to heat”. The opposite of an endothermic process is an exothermic
Exothermic

File:Explosion1.JPG In thermodynamics, the term exothermic describes a process or reaction that releases energy usually in the form of heat, but also in form of light , electricity , or sound....
 process, one that releases energy in the form of heat. The term “endothermic” was coined by Marcellin Berthelot
Marcellin Berthelot

Marcellin Pierre Eug?ne Berthelot was a French chemist and politician noted in thermochemistry for the Thomsen-Berthelot principle. He synthesized many organic compounds from inorganic substances and so utterly disproved the theory of vitalism....
.

The concept is frequently applied in physical sciences to e.g.






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In thermodynamics
Thermodynamics

In physics, thermodynamics is the study of the conversion of heat energy into different forms of energy ; different energy conversions into heat energy; and its relation to macroscopic variables such as temperature, pressure, and volume....
, the word endothermic "within-heating" describes a process or reaction that absorbs energy in the form of heat
Heat

In physics and thermodynamics, heat is any transfer of energy from one body or thermodynamic system to another due to a difference in temperature....
. Its etymology stems from the Greek prefix endo-, meaning “inside” and the Greek suffix –thermic, meaning “to heat”. The opposite of an endothermic process is an exothermic
Exothermic

File:Explosion1.JPG In thermodynamics, the term exothermic describes a process or reaction that releases energy usually in the form of heat, but also in form of light , electricity , or sound....
 process, one that releases energy in the form of heat. The term “endothermic” was coined by Marcellin Berthelot
Marcellin Berthelot

Marcellin Pierre Eug?ne Berthelot was a French chemist and politician noted in thermochemistry for the Thomsen-Berthelot principle. He synthesized many organic compounds from inorganic substances and so utterly disproved the theory of vitalism....
.

The concept is frequently applied in physical sciences to e.g. chemical reactions, where thermal energy
Thermal energy

Thermal energy is a form of energy that manifests itself as an increase of temperature. It is also the sum of sensible heat and latent heat....
 (heat) is converted to chemical bond energy
Bond energy

In chemistry, bond energy is a measure of bond strength in a chemical bond. For example the carbon-hydrogen bond energy in methane E is the enthalpy change involved with breaking up one molecule of methane into a carbon atom and 4 hydrogen Radical s divided by 4....
.

Overview

Endothermic, also incorrectly known as endergonic, refers to a transformation in which a system receives heat from the surroundings:
Q > 0


When the occurs at constant pressure:

?H > 0


and constant volume:

?U > 0


If the surroundings do not supply heat (e.g., when the system is adiabatic
Adiabatic process

In thermodynamics, an adiabatic process or an isocaloric process is a thermodynamic process in which no heat is transferred to or from the working fluid....
), an endothermic transformation leads to a decrease in the temperature of the system.

Endothermic processes

Some examples of endothermic processes are:
  • Depressurising a pressure can
  • A chemical cold pack consisting primarily of ammonium nitrate
    Ammonium nitrate

    The chemical compound ammonium nitrate, the nitrate of ammonia with the chemical formula NitrogenHydrogen4NitrogenOxygen3, is a white powder at room temperature and standard pressure....
     and water
    Water

    Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
    .


Implications for chemical reactions

Chemical endothermic reactions need heat to be performed. In a thermochemical reaction that is endothermic, the heat is placed on the reactants side (heat is necessary for and absorbed during the reaction).

See also

  • Exothermic
    Exothermic

    File:Explosion1.JPG In thermodynamics, the term exothermic describes a process or reaction that releases energy usually in the form of heat, but also in form of light , electricity , or sound....
  • Endergonic
    Endergonic

    Endergonic means absorbing energy in the form of work. Its etymology stems from the suffix -ergonic, as derived from the Greek root ergon, meaning work , combined with the prefix end-, as derived from the Greek root en, meaning put into....
    • Endergonic reaction
      Endergonic reaction

      In thermochemistry, an endergonic reaction is a chemical reaction in which the standard change in Thermodynamic free energy is positive, and energy is absorbed....
  • Exergonic
    Exergonic

    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 work , combined with the Greek prefix ex-, meaning out of....
    • Exergonic reaction
      Exergonic reaction

      An exergonic reaction is a chemical reaction where the change in the Gibbs free energy is negative, indicating a spontaneous reaction. Symbolically, the release of Gibbs free energy, G, in an exergonic reaction is denoted as...


External links

  • - MSDS Hyper-Glossary