An endothermic process is a chemical or physical process that absorbs heat from its surroundings. In terms of thermodynamics and thermochemistry, it is a thermodynamic process with an increase in the enthalpyH (or internal energyU) of the system.[1] In an endothermic process, the heat that a system absorbs is thermal energy transfer into the system. Thus, an endothermic reaction generally leads to an increase in the temperature of the system and a decrease in that of the surroundings.
The term was coined by 19th-century French chemist Marcellin Berthelot. The term endothermic comes from the Greek ἔνδον (endon) meaning 'within' and θερμ- (therm) meaning 'hot' or 'warm'.
An endothermic process may be a chemical process, such as dissolving ammonium nitrate (NH4NO3) in water (H2O), or a physical process, such as the melting of ice cubes.
The opposite of an endothermic process is an exothermic process, one that releases or "gives out" energy, usually in the form of heat and sometimes as electrical energy. Thus, endo in endothermic refers to energy or heat going in, and exo in exothermic refers to energy or heat going out. In each term (endothermic and exothermic) the prefix refers to where heat (or electrical energy) goes as the process occurs.
Due to bonds breaking and forming during various processes (changes in state, chemical reactions), there is usually a change in energy. If the energy of the forming bonds is greater than the energy of the breaking bonds, then energy is released. This is known as an exothermic reaction. However, if more energy is needed to break the bonds than the energy being released, energy is taken up. Therefore, it is an endothermic reaction.[2]
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Whether a process can occur spontaneously depends not only on the enthalpy change but also on the entropy change (∆S) and absolute temperatureT. If a process is a spontaneous process at a certain temperature, the products have a lower Gibbs free energyG = H – TS than the reactants (an exergonic process),[1] even if the enthalpy of the products is higher. Thus, an endothermic process usually requires a favorable entropy increase (∆S > 0) in the system that overcomes the unfavorable increase in enthalpy so that still ∆G < 0. While endothermic phase transitions into more disordered states of higher entropy, e.g. melting and vaporization, are common, spontaneous chemical processes at moderate temperatures are rarely endothermic. The enthalpy increase ∆H ≫ 0 in a hypothetical strongly endothermic process usually results in ∆G = ∆H – T∆S > 0, which means that the process will not occur (unless driven by electrical or photon energy). An example of an endothermic and exergonic process is
High-energy neutrons can produce tritium from lithium-7 in an endothermic process, consuming 2.466 MeV. This was discovered when the 1954 Castle Bravo nuclear test produced an unexpectedly high yield.[3]
The terms "endothermic" and "endotherm" are both derived from Greekἔνδονendon "within" and θέρμηthermē "heat", but depending on context, they can have very different meanings.
In physics, thermodynamics applies to processes involving a system and its surroundings, and the term "endothermic" is used to describe a reaction where energy is taken "(with)in" by the system (vs. an "exothermic" reaction, which releases energy "outwards").
In biology, thermoregulation is the ability of an organism to maintain its body temperature, and the term "endotherm" refers to an organism that can do so from "within" by using the heat released by its internal bodily functions (vs. an "ectotherm", which relies on external, environmental heat sources) to maintain an adequate temperature.
^"Exothermic & Endothermic Reactions". Energy Foundations for High School Chemistry. American Chemical Society. Retrieved 2021-04-11.
^Austin, Patrick (January 1996). "Tritium: The environmental, health, budgetary, and strategic effects of the Department of Energy's decision to produce tritium". Institute for Energy and Environmental Research. Retrieved 2010-09-15.
^Qian, Y.-Z.; Vogel, P.; Wasserburg, G. J. (1998). "Diverse Supernova Sources for the r-Process". Astrophysical Journal 494 (1): 285–296. arXiv:astro-ph/9706120. Bibcode:1998ApJ...494..285Q. doi:10.1086/305198.
^"Messing with Mass". PBS. WGBH. 2005. Retrieved 2020-05-28.
External linksedit
Exothermic and Endothermic – MSDS Hyper-Glossary at Interactive Learning Paradigms, Incorporated
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This article is about the physical effect For self maintained thermal homeostasis see Endotherm This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations June 2018 Learn how and when to remove this template message An endothermic process is a chemical or physical process that absorbs heat from its surroundings In terms of thermodynamics and thermochemistry it is a thermodynamic process with an increase in the enthalpy H or internal energy U of the system 1 In an endothermic process the heat that a system absorbs is thermal energy transfer into the system Thus an endothermic reaction generally leads to an increase in the temperature of the system and a decrease in that of the surroundings The term was coined by 19th century French chemist Marcellin Berthelot The term endothermic comes from the Greek ἔndon endon meaning within and 8erm therm meaning hot or warm An endothermic process may be a chemical process such as dissolving ammonium nitrate NH4NO3 in water H2O or a physical process such as the melting of ice cubes The opposite of an endothermic process is an exothermic process one that releases or gives out energy usually in the form of heat and sometimes as electrical energy Thus endo in endothermic refers to energy or heat going in and exo in exothermic refers to energy or heat going out In each term endothermic and exothermic the prefix refers to where heat or electrical energy goes as the process occurs Contents 1 In chemistry 2 Details 3 Examples 4 Distinction between endothermic and endotherm 5 References 6 External linksIn chemistry edit source source source The formation of barium thiocyanate from ammonium thiocyanate and barium hydroxide is so endothermic that it can freeze a beaker to wet styrofoamDue to bonds breaking and forming during various processes changes in state chemical reactions there is usually a change in energy If the energy of the forming bonds is greater than the energy of the breaking bonds then energy is released This is known as an exothermic reaction However if more energy is needed to break the bonds than the energy being released energy is taken up Therefore it is an endothermic reaction 2 Details editWhether a process can occur spontaneously depends not only on the enthalpy change but also on the entropy change S and absolute temperature T If a process is a spontaneous process at a certain temperature the products have a lower Gibbs free energy G H TS than the reactants an exergonic process 1 even if the enthalpy of the products is higher Thus an endothermic process usually requires a favorable entropy increase S gt 0 in the system that overcomes the unfavorable increase in enthalpy so that still G lt 0 While endothermic phase transitions into more disordered states of higher entropy e g melting and vaporization are common spontaneous chemical processes at moderate temperatures are rarely endothermic The enthalpy increase H 0 in a hypothetical strongly endothermic process usually results in G H T S gt 0 which means that the process will not occur unless driven by electrical or photon energy An example of an endothermic and exergonic process is C 6 H 12 O 6 6 H 2 O 12 H 2 6 CO 2 displaystyle ce C6H12O6 6 H2O gt 12 H2 6 CO2 nbsp D r H 627 kJ mol D r G 31 kJ mol displaystyle Delta r H circ 627 text kJ mol quad Delta r G circ 31 text kJ mol nbsp Examples editEvaporation Sublimation Cracking of alkanes Thermal decomposition Hydrolysis Nucleosynthesis of elements heavier than nickel in stellar cores High energy neutrons can produce tritium from lithium 7 in an endothermic process consuming 2 466 MeV This was discovered when the 1954 Castle Bravo nuclear test produced an unexpectedly high yield 3 Nuclear fusion of elements heavier than iron in supernovae 4 Dissolving together barium hydroxide and ammonium chloride Dissolving together citric acid and baking soda 5 Distinction between endothermic and endotherm editThe terms endothermic and endotherm are both derived from Greek ἔndon endon within and 8ermh therme heat but depending on context they can have very different meanings In physics thermodynamics applies to processes involving a system and its surroundings and the term endothermic is used to describe a reaction where energy is taken with in by the system vs an exothermic reaction which releases energy outwards In biology thermoregulation is the ability of an organism to maintain its body temperature and the term endotherm refers to an organism that can do so from within by using the heat released by its internal bodily functions vs an ectotherm which relies on external environmental heat sources to maintain an adequate temperature References edit a b Oxtoby D W Gillis H P Butler L J 2015 Principle of Modern Chemistry Brooks Cole p 617 ISBN 978 1305079113 Exothermic amp Endothermic Reactions Energy Foundations for High School Chemistry American Chemical Society Retrieved 2021 04 11 Austin Patrick January 1996 Tritium The environmental health budgetary and strategic effects of the Department of Energy s decision to produce tritium Institute for Energy and Environmental Research Retrieved 2010 09 15 Qian Y Z Vogel P Wasserburg G J 1998 Diverse Supernova Sources for the r Process Astrophysical Journal 494 1 285 296 arXiv astro ph 9706120 Bibcode 1998ApJ 494 285Q doi 10 1086 305198 Messing with Mass PBS WGBH 2005 Retrieved 2020 05 28 External links editExothermic and Endothermic MSDS Hyper Glossary at Interactive Learning Paradigms IncorporatedPortal nbsp Chemistry Retrieved from https en wikipedia org w index php title Endothermic process amp oldid 1186065512, wikipedia, wiki, book, books, library,
