https://www.sciencemadness.org/smwiki/index.php?title=Standard_enthalpy_of_formation&feed=atom&action=historyStandard enthalpy of formation - Revision history2024-03-29T13:15:21ZRevision history for this page on the wikiMediaWiki 1.25.1https://www.sciencemadness.org/smwiki/index.php?title=Standard_enthalpy_of_formation&diff=14356&oldid=prevMabus: Mabus moved page Standard enthalpy change of formation to Standard enthalpy of formation: Better link2022-01-09T11:58:24Z<p>Mabus moved page <a href="/smwiki/index.php/Standard_enthalpy_change_of_formation" class="mw-redirect" title="Standard enthalpy change of formation">Standard enthalpy change of formation</a> to <a href="/smwiki/index.php/Standard_enthalpy_of_formation" title="Standard enthalpy of formation">Standard enthalpy of formation</a>: Better link</p>
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</td></tr></table>Mabushttps://www.sciencemadness.org/smwiki/index.php?title=Standard_enthalpy_of_formation&diff=14355&oldid=prevMabus: Created page with "{{Stub}} The '''standard enthalpy of formation''' or '''standard heat of formation''' of a compound is the change of enthalpy during the formation of 1 mole of the substan..."2022-01-09T11:57:34Z<p>Created page with "{{Stub}} The '''standard enthalpy of formation''' or '''standard heat of formation''' of a compound is the change of <a href="/smwiki/index.php?title=Enthalpy&action=edit&redlink=1" class="new" title="Enthalpy (page does not exist)">enthalpy</a> during the formation of 1 mole of the substan..."</p>
<p><b>New page</b></p><div>{{Stub}}<br />
The '''standard enthalpy of formation''' or '''standard heat of formation''' of a compound is the change of [[enthalpy]] during the formation of 1 mole of the substance from its constituent elements, with all substances in their standard states. The standard pressure value ''p''<sup>⦵</sup> 10<sup>5</sup> Pa (= 100 kPa = 1 bar) is recommended by [[International Union of Pure and Applied Chemistry|IUPAC]], although prior to 1982 the value 1.00 atm (101.325 kPa) was used.<ref>https://goldbook.iupac.org/terms/view/S05921</ref> There is no standard temperature. Its symbol is Δ<sub>f</sub>''H''<sup>⦵</sup>. The superscript |Plimsoll on this symbol indicates that the process has occurred under standard conditions at the specified temperature (usually 25 °C or 298.15 K). Standard states are as follows:<br />
*For a gas: the hypothetical state it would have assuming it obeyed the ideal gas equation at a pressure of 1 bar<br />
*For a gaseous or solid solute present in a diluted ideal solution: the hypothetical state of concentration of the solute of exactly one mole per liter (1 [[molar concentration|M]]) at a pressure of 1 bar extrapolated from infinite dilution<br />
*For a pure substance or a [[solvent]] in a condensed state (a liquid or a solid): the standard state is the pure liquid or solid under a pressure of 1 bar<br />
*For an element: the form in which the element is most stable under 1 bar of pressure. One exception is [[phosphorus]], for which the most stable form at 1 bar is black phosphorus, but white phosphorus is chosen as the standard reference state for zero enthalpy of formation.<ref>{{cite book|url=https://books.google.com/books?id=fJWpg4ZJ2esC&q=standard+exception+white+phosphorus+enthalpy&pg=PA547 |title=Principles of Modern Chemistry|isbn=978-0-8400-4931-5|page=547|last1=Oxtoby|first1=David W|last2=Pat Gillis|first2=H|last3=Campion|first3=Alan|date=2011}}</ref><br />
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==References==<br />
<references/><br />
===Relevant Sciencemadness threads===<br />
*[http://www.sciencemadness.org/talk/viewthread.php?tid=18494 Calculate Enthalpy of Different Reactions]<br />
*[http://www.sciencemadness.org/talk/viewthread.php?tid=17318 Enthalpy question]<br />
*[http://www.sciencemadness.org/talk/viewthread.php?tid=11360 Delta Heat of Formation question]<br />
*[https://www.sciencemadness.org/whisper/viewthread.php?tid=156096 68% Nitric Acid Enthalpy of Formation]<br />
*[http://www.sciencemadness.org/talk/viewthread.php?tid=11195 Computing energetic properties and crystal density of energetic materials]<br />
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[[Category:Concepts]]<br />
[[Category:Thermodynamics]]</div>Mabus