Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Endothermic process
open-in-new
<h2 id="in-chemistry">In chemistry</h2> <p>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.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p> <h2 id="details">Details</h2> <p>Whether a process can occur spontaneously depends not only on the <a href="/facts/Enthalpy/bBou8lCE">enthalpy</a> change but also on the <a href="/facts/Entropy/s52IXeFz">entropy</a> change (∆<i>S</i>) and <a href="/facts/Thermodynamic_temperature/JXeJJPa6">absolute temperature</a> T. If a process is a <a href="/facts/Spontaneous_process/xyGhdUG0">spontaneous process</a> at a certain temperature, the products have a lower <a href="/facts/Thermodynamic_free_energy/GtjtQqnq">Gibbs free energy</a> <i>G</i> = <i>H</i> – <i>TS</i> than the reactants (an <a href="/facts/Exergonic_process/2kPJobE7">exergonic process</a>),<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> even if the enthalpy of the products is higher. Thus, an endothermic process usually requires a <a href="/facts/Entropy_production/HxNR6Yza">favorable entropy increase</a> (∆<i>S</i> > 0) in the system that overcomes the unfavorable increase in enthalpy so that still ∆<i>G</i> < 0. While endothermic <a href="/facts/Phase_transition/eLP2BY8R">phase transitions</a> into more disordered states of higher entropy, e.g. melting and vaporization, are common, spontaneous chemical processes at moderate temperatures are rarely endothermic.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> The enthalpy increase ∆<i>H</i> ≫ 0 in a hypothetical strongly endothermic process usually results in ∆<i>G</i> = ∆<i>H</i> – <i>T</i>∆<i>S</i> > 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 </p> C 6 H 12 O 6 + 6 H 2 O ⟶ 12 H 2 + 6 CO 2 {\displaystyle {\ce {C6H12O6 + 6 H2O -> 12 H2 + 6 CO2}}} Δ r H ∘ = + 627 kJ/mol , Δ r G ∘ = − 31 kJ/mol {\displaystyle \Delta _{r}H^{\circ }=+627\ {\text{kJ/mol}},\quad \Delta _{r}G^{\circ }=-31\ {\text{kJ/mol}}} . <h2 id="examples">Examples</h2> <ul><li><a href="/facts/Evaporation/tgvIlJys">Evaporation</a></li> <li><a href="/facts/Sublimation_(phase_transition)/KDoKokMn">Sublimation</a></li> <li><a href="/facts/Cracking_(chemistry)/EBLtwW4g">Cracking</a> of <a href="/facts/Alkane/Qam7Hvmf">alkanes</a></li> <li><a href="/facts/Thermal_decomposition/Qqx9RqkW">Thermal decomposition</a></li> <li><a href="/facts/Hydrolysis/JTvwIHPs">Hydrolysis</a></li> <li><a href="/facts/Nucleosynthesis/F9MIeADF">Nucleosynthesis</a> of elements heavier than <a href="/facts/Nickel/KwMCHYRP">nickel</a> in stellar cores<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a></li> <li>High-energy neutrons can produce <a href="/facts/Tritium/HWSa6EHy">tritium</a> from <a href="/facts/Lithium-7/XC311sQu">lithium-7</a> in an endothermic process, consuming 2.466 <a href="/facts/MeV/YMT1fqX9">MeV</a>. This was discovered when the 1954 <a href="/facts/Castle_Bravo/R2F4BRFf">Castle Bravo</a> nuclear test produced an unexpectedly high yield.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></li> <li><a href="/facts/Nuclear_fusion/hP0gLDqj">Nuclear fusion</a> of elements heavier than <a href="/facts/Iron/QK1JYy8E">iron</a> in <a href="/facts/Supernova/Pfo2J23l">supernovae</a><a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a></li> <li>Dissolving together <a href="/facts/Barium_hydroxide/4nLXpQPQ">barium hydroxide</a> and <a href="/facts/Ammonium_chloride/SfXdntlv">ammonium chloride</a></li></ul> <h2 id="distinction-between-endothermic-and-endotherm">Distinction between endothermic and endotherm</h2> <p>The terms "endothermic" and "endotherm" are both derived from <a href="/facts/Ancient_Greek/LIK7NlUh">Greek</a> ἔνδον <i><i>endon</i></i> "within" and θέρμη <i><i>thermē</i></i> "heat", but depending on context, they can have very different meanings. </p><p>In physics, <a href="/facts/Thermodynamics/q4hIx3yP">thermodynamics</a> 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").<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a><a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p><p>In biology, <a href="/facts/Thermoregulation/V692hIjw">thermoregulation</a> is the ability of an <a href="/facts/Organism/j8JkL09u">organism</a> to maintain its body temperature, and the term "<a href="/facts/Endotherm/qs3DIGHx">endotherm</a>" refers to an organism that can do so from "within" by using the heat released by its internal bodily functions (vs. an "<a href="/facts/Ectotherm/vdjXLuQr">ectotherm</a>", which relies on external, environmental heat sources) to maintain an adequate temperature.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> </p> <h2 id="external-links">External links</h2> <ul><li><a href="http://www.ilpi.com/msds/ref/exothermic.html">Exothermic and Endothermic</a> – MSDS Hyper-Glossary at Interactive Learning Paradigms, Incorporated</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"17.3: Exothermic and Endothermic Processes". Chemistry LibreTexts. 2016-06-27. Retrieved 2024-06-26. <a href="https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/17%3A_Thermochemistry/17.03%3A_Exothermic_and_Endothermic_Processes" target="_blank">https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/17%3A_Thermochemistry/17.03%3A_Exothermic_and_Endothermic_Processes</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Oxtoby, D. W; Gillis, H.P., Butler, L. J. (2015). Principle of Modern Chemistry, Brooks Cole. p. 617. ISBN 978-1305079113 <a href="//archive.org/details/principlesofmode0000oxto" target="_blank">//archive.org/details/principlesofmode0000oxto</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"17.3: Exothermic and Endothermic Processes". Chemistry LibreTexts. 2016-06-27. Retrieved 2024-06-26. <a href="https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/17%3A_Thermochemistry/17.03%3A_Exothermic_and_Endothermic_Processes" target="_blank">https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/17%3A_Thermochemistry/17.03%3A_Exothermic_and_Endothermic_Processes</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Sutton, Mike (2007-03-01). "Chemistry for the common good". Chemistry World. Retrieved 2024-06-26. <a href="https://www.chemistryworld.com/features/chemistry-for-the-common-good/3004535.article" target="_blank">https://www.chemistryworld.com/features/chemistry-for-the-common-good/3004535.article</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"endothermic | Etymology of endothermic by etymonline". www.etymonline.com. Retrieved 2024-06-28. <a href="https://www.etymonline.com/word/endothermic" target="_blank">https://www.etymonline.com/word/endothermic</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Lu, Jue Xi; Tupper, Connor; Gutierrez, Alejandra V.; Murray, John (2024), "Biochemistry, Dissolution and Solubility", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 28613752, retrieved 2024-06-28 <a href="http://www.ncbi.nlm.nih.gov/books/NBK431100/" target="_blank">http://www.ncbi.nlm.nih.gov/books/NBK431100/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"17.3: Exothermic and Endothermic Processes". Chemistry LibreTexts. 2016-06-27. Retrieved 2024-06-26. <a href="https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/17%3A_Thermochemistry/17.03%3A_Exothermic_and_Endothermic_Processes" target="_blank">https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/17%3A_Thermochemistry/17.03%3A_Exothermic_and_Endothermic_Processes</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"Endothermic & Exothermic Reactions" (PDF). Ashrae. Retrieved 2024-06-28. <a href="https://www.ashrae.org/file%20library/communities/student%20zone/k-12%20activities/ashrae-endothermic---exothermic-reactions-stem-kit.pdf" target="_blank">https://www.ashrae.org/file%20library/communities/student%20zone/k-12%20activities/ashrae-endothermic---exothermic-reactions-stem-kit.pdf</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"Exothermic & Endothermic Reactions". Energy Foundations for High School Chemistry. American Chemical Society. Retrieved 2021-04-11. <a href="https://highschoolenergy.acs.org/content/hsef/en/how-can-energy-change/exothermic-endothermic.html" target="_blank">https://highschoolenergy.acs.org/content/hsef/en/how-can-energy-change/exothermic-endothermic.html</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Oxtoby, D. W; Gillis, H.P., Butler, L. J. (2015). Principle of Modern Chemistry, Brooks Cole. p. 617. ISBN 978-1305079113 <a href="//archive.org/details/principlesofmode0000oxto" target="_blank">//archive.org/details/principlesofmode0000oxto</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>"Examples of Spontaneous Endothermic Reactions - Chemistry Examples". www.chemicool.com. Retrieved 2024-06-28. <a href="https://www.chemicool.com/examples/spontaneous-endothermic-reactions.html#:~:text=Hence%20reactions%20are%20spontaneous%20only,in%20free%20energy,%20is%20negative.&text=Exothermic%20reactions%20have%20negative%20values,with%20positive%20values%20of%20%CE%94H." target="_blank">https://www.chemicool.com/examples/spontaneous-endothermic-reactions.html#:~:text=Hence%20reactions%20are%20spontaneous%20only,in%20free%20energy,%20is%20negative.&text=Exothermic%20reactions%20have%20negative%20values,with%20positive%20values%20of%20%CE%94H.</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"Galactic nucleosynthesis: the onset of element production in our galaxy". Research Features. 2017-05-15. Retrieved 2024-06-28. <a href="https://researchfeatures.com/galactic-nucleosynthesis/" target="_blank">https://researchfeatures.com/galactic-nucleosynthesis/</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>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. <a href="http://www.ieer.org/reports/tritium.html#(11)" target="_blank">http://www.ieer.org/reports/tritium.html#(11)</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>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. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>"5.2: The First Law of Thermodynamics". Chemistry LibreTexts. 2014-11-18. Retrieved 2024-06-28. <a href="https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Chemistry_-_The_Central_Science_(Brown_et_al.)/05%3A_Thermochemistry/5.02%3A_The_First_Law_of_Thermodynamics" target="_blank">https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Chemistry_-_The_Central_Science_(Brown_et_al.)/05%3A_Thermochemistry/5.02%3A_The_First_Law_of_Thermodynamics</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>"Meaning of endothermic in English". Cambridge Dictionary. Cambridge University Press. <a href="https://dictionary.cambridge.org/dictionary/english/endothermic" target="_blank">https://dictionary.cambridge.org/dictionary/english/endothermic</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>"Endotherm | Homeothermy, Thermoregulation, Metabolism | Britannica". www.britannica.com. Retrieved 2024-06-28. <a href="https://www.britannica.com/science/endotherm" target="_blank">https://www.britannica.com/science/endotherm</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> </ol>