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It is defined as one kilocalorie of energy (1000 thermochemical gram calories) per one mole of substance. The unit symbol is written kcal/mol or kcal⋅mol −1. As typically measured, one kcal/mol represents a temperature increase of one degree Celsius in one liter of water (with a mass of 1 kg) resulting from the reaction of one mole of reagents.
For gases, departure from 3 R per mole of atoms is generally due to two factors: (1) failure of the higher quantum-energy-spaced vibration modes in gas molecules to be excited at room temperature, and (2) loss of potential energy degree of freedom for small gas molecules, simply because most of their atoms are not bonded maximally in space to ...
The SI unit of molar heat capacity heat is joule per kelvin per mole (J/(K⋅mol), J/(K mol), J K −1 mol −1, etc.). Since an increment of temperature of one degree Celsius is the same as an increment of one kelvin, that is the same as joule per degree Celsius per mole (J/(°C⋅mol)).
These tables list values of molar ionization energies, measured in kJ⋅mol −1. This is the energy per mole necessary to remove electrons from gaseous atoms or atomic ions. The first molar ionization energy applies to the neutral atoms.
In other scientific contexts, the term "calorie" and the symbol "cal" almost always refers to the small unit; the "large" unit being generally called "kilocalorie" with symbol "kcal". It is mostly used to express the amount of energy released in a chemical reaction or phase change, typically per mole of substance, as in kilocalories per mole. [32]
The standard enthalpy of formation is measured in units of energy per amount of substance, usually stated in kilojoule per mole (kJ mol −1), but also in kilocalorie per mole, joule per mole or kilocalorie per gram (any combination of these units conforming to the energy per mass or amount guideline).
7 N nitrogen (N 2) use (N 2) 0.720 CRC (N 2) 0.71 LNG (N 2) 0.720 WEL (per mol N atoms) 0.36 8 O oxygen (O 2) use (O 2) 0.444 CRC (O 2) 0.44 LNG (O 2) 0.444 WEL (per mol O atoms) 0.222 9 F fluorine (F 2) use (F 2) 0.510 CRC (F 2) 0.51 LNG (F 2) 0.510 WEL (per mol F atoms) 0.26 10 Ne neon; use: 0.335 CRC: 0.328 LNG: 0.335 WEL: 0.34 11 Na sodium ...
In chemistry, it is expressed as the energy to ionize a mole of atoms or molecules, usually as kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol). [3] Comparison of ionization energies of atoms in the periodic table reveals two periodic trends which follow the rules of Coulombic attraction: [4]