The joule per mole (symbol: J·mol−1 or J/mol) is the unit of energy per amount of substance in the International System of Units (SI), such that energy is measured in joules, and the amount of substance is measured in moles.
It is also an SI derived unit of molar thermodynamic energy defined as the energy equal to one joule in one mole of substance.[1][2] For example, the Gibbs free energy of a compound in the area of thermochemistry is often quantified in units of kilojoules per mole (symbol: kJ·mol−1 or kJ/mol), with 1 kilojoule = 1000 joules.[3]
Physical quantities measured in J·mol−1 usually describe quantities of energy transferred during phase transformations or chemical reactions. Division by the number of moles facilitates comparison between processes involving different quantities of material and between similar processes involving different types of materials. The precise meaning of such a quantity is dependent on the context (what substances are involved, circumstances, etc.), but the unit of measurement is used specifically to describe certain existing phenomena, such as in thermodynamics it is the unit of measurement that describes molar energy.[4]
Since 1 mole = 6.02214076×1023 particles (atoms, molecules, ions etc.), 1 joule per mole is equal to 1 joule divided by 6.02214076×1023 particles, ≈1.660539×10−24 joule per particle. This very small amount of energy is often expressed in terms of an even larger unit such as the kJ·mol−1, because of the typical order of magnitude for energy changes in chemical processes. For example, heats of fusion and vaporization are usually of the order of 10 kJ·mol−1, bond energies are of the order of 100 kJ·mol−1, and ionization energies of the order of 1000 kJ·mol−1. [5] For this reason, it is common within the field of chemistry to quantify the enthalpy of reaction in units of kJ·mol−1.[6]
Other units sometimes used to describe reaction energetics are kilocalories per mole (kcal·mol−1), electron volts per particle (eV), and wavenumbers in inverse centimeters (cm−1). 1 kJ·mol−1 is approximately equal to 1.04×10−2 eV per particle, 0.239 kcal·mol−1, or 83.6 cm−1. At room temperature (25 °C, or 298.15 K) 1 kJ·mol−1 is approximately equal to 0.4034 .
^"What does Joule per Mole mean? Definition, meaning and sense". www.tititudorancea.com. Retrieved 2020-06-05.
^"Calorimetry and Molar Enthalpy". Retrieved 2021-03-05.
^"Units in Thermochemical Calculations – AP Central | College Board". apcentral.collegeboard.org. Retrieved 2023-05-21.
^McGlashan, M. L. (2007-10-31). Chemical Thermodynamics: Volume 1. Royal Society of Chemistry. ISBN 978-1-84755-582-3.
^Schroeder, Daniel (1999). An Introduction to Thermal Physics. ISBN 978-0201380279.
^"5.4: Enthalpy of Reaction". Chemistry LibreTexts. 2014-11-18. Retrieved 2023-05-21.
The joulepermole (symbol: J·mol−1 or J/mol) is the unit of energy per amount of substance in the International System of Units (SI), such that energy...
different quantities may share the same coherent SI unit. For example, the jouleper kelvin (symbol J/K) is the coherent SI unit for two distinct quantities:...
example, the square metre (m2), the SI derived unit of area; and the kilogram per cubic metre (kg/m3 or kg⋅m−3), the SI derived unit of density. The names...
heat energy released in an exothermic reaction is converted to ΔH⚬ in Joulepermole (formerly cal/mol). The standard enthalpy change ΔH⚬ is essentially...
substance, usually stated in kilojoule permole (kJ mol−1), but also in kilocalorie permole, joulepermole or kilocalorie per gram (any combination of these...
9477×10−21 joulesper molecule, or about 0.043 eV per molecule. At room temperature (25 °C, 77 °F, or 298.15 K), one kilocalorie permole is approximately...
produce a unit change in its temperature. The SI unit of heat capacity is jouleper kelvin (J/K). Heat capacity is an extensive property. The corresponding...
Ricci tensor reciprocal square meter (m−2) radiancy meter per second gas constant joulepermoleper kelvin (J⋅mol−1⋅K−1) r {\displaystyle \mathbf {r} } radius...
substance is measured as a number of moles, one gets the molar heat capacity instead, whose SI unit is jouleper kelvin permole, J⋅mol−1⋅K−1. If the amount is...
where m is the mass of the system. The SI unit for specific enthalpy is jouleper kilogram. It can be expressed in other specific quantities by h = u +...
{\displaystyle P^{0}} is usually given the symbol S°, and has units of joulespermoleper kelvin (J⋅mol−1⋅K−1). Unlike standard enthalpies of formation, the...
derived unit of energy, the joule (J), or the kilojoule (kJ) for 1000 joules. The precise equivalence between calories and joules has varied over the years...
chemical component. (SI unit: joulesper particle or joulespermole) Ni is the number of particles (or number of moles) composing the i-th chemical component...
denoted "e.u." or "eU" and equal to one calorie per kelvin permole, or 4.184 joulesper kelvin permole. Entropy units are primarily used in chemistry...
a solute in a solvent. Chemical potential has units of joulespermole (J/mol), or energy per amount of matter. Chemical potential can be used to characterize...
number of moles in the sample (as is sometimes done in chemistry), one gets the molar heat capacity (whose SI unit is jouleper kelvin permole, J⋅K−1⋅mol−1)...
(1 J⋅kg−1). The sievert (Sv) is equal to one jouleper kilogram (1 J⋅kg−1). The katal (kat) is equal to one moleper second (1 mol⋅s−1). Furthermore, there...
to the Faraday constant (F ≈ 96485 C⋅mol−1), where the energy in joules of n moles of particles each with energy E eV is equal to E·F·n. Orders of magnitude...
fus {\displaystyle \Delta S_{\text{fus}}} and normally expressed in joulespermole-kelvin, J/(mol·K). A natural process such as a phase transition will...
joule energy Derived SI unit with a special name joulepermole energy per amount of substance Derived coherent SI unit without a special name joule-second...
generators, inductors, and transformers. In ordinary conductors, they cause Joule heating, which creates light in incandescent light bulbs. Time-varying currents...
{\displaystyle \Delta S_{\text{vap}}^{\ominus }} and normally expressed in joulespermole-kelvin, J/(mol·K). For a phase transition such as vaporization or fusion...
62607015×10−34 joule-second (J⋅s). The elementary charge e is exactly 1.602176634×10−19 coulomb (C). The Boltzmann constant k is exactly 1.380649×10−23 jouleper kelvin...
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