View source for Kilocalorie per mole

{{Short description|Unit for measuring energy}}
The '''kilocalorie per mole''' is a unit to measure an amount of [[energy]] per number of [[molecule]]s, [[atom]]s, or other similar [[particle]]s.  It is defined as one [[kilocalorie]] of energy (1000 thermochemical gram [[calorie]]s) per one [[mole (unit)|mole]] of substance.  The unit symbol is written kcal/mol or kcal⋅mol<sup>−1</sup>. As typically measured, one kcal/mol represents a temperature increase of one degree Celsius in one liter of water (with a mass of 1&nbsp;kg) resulting from the reaction of one mole of reagents.

In [[SI units]], one kilocalorie per mole is equal to 4.184 [[joule per mole|kilojoules per mole]] (kJ/mol), which comes to approximately {{Val|6.9477|e=-21}} [[joule]]s per molecule, or about 0.043&nbsp;[[electron volt|eV]] per molecule. At [[room temperature]] (25&nbsp;°C, 77&nbsp;°F, or 298.15&nbsp;K) it is approximately equal to 1.688 [[kT (energy)|units in the ''kT'' term]] of [[Boltzmann's equation]].

Even though it is not an SI unit, the kilocalorie per mole is still widely used in [[chemistry]]<ref name=Zvi/> and [[biology]]<ref name=Cooper/> for [[thermodynamics|thermodynamical]] quantities such as [[thermodynamic free energy]], [[heat of vaporization]], [[heat of fusion]] and [[ionization energy]]. This is due to a variety of factors, including the ease with which it can be calculated based on the units of measure typically employed in quantifying a chemical reaction, especially in aqueous solution. In addition, for many important biological processes, thermodynamic changes are on a convenient order of magnitude when expressed in kcal/mol. For example, for the reaction of [[glucose]] with [[Adenosine 5'-triphosphate|ATP]] to form [[Glucose 6-phosphate|glucose-6-phosphate]] and [[Adenosine diphosphate|ADP]], the free energy of reaction is −4.0&nbsp;kcal/mol using the pH = 7 [[standard state]].<ref name=Cooper/>

==References==
<references>
<ref name=Zvi>
 {{cite book |first= Robert D. |last= Bach |editor-first= Zvi |editor-last= Rappoport |year= 2006 |chapter-url= https://books.google.com/books?id=4PdYwo25VP8C&pg=PA12 |title= The Chemistry of Peroxides, Volume 2 |chapter= General and Theoretical Aspects of the Peroxide Group |page= 12 |location= Chichester |publisher= Wiley |isbn= 9780470862759}}
</ref>
<ref name=Cooper>
 {{cite book |last1=Cooper |first1=G.M. |title=The Cell: A Molecular Approach |publisher=Sinauer Associates |location=Sunderland, Massachusetts |url=https://www.ncbi.nlm.nih.gov/books/NBK9903/ |access-date=20 July 2022}}
</ref> 
</references>

{{DEFAULTSORT:Kilocalorie Per Mole}}
[[Category:Energy (physics)]]
[[Category:Thermodynamics]]
[[Category:Heat transfer]]
[[Category:Units of chemical measurement]]


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