Molar energy converter
Convert between kJ/mol, kcal/mol, eV and cm⁻¹, the four ways chemistry and physics write the same quantity of energy.
That's 1.25× as strong as a typical activation energy, while a carbon–carbon single bond is 3.5× higher. That is about 40.34 times the thermal energy available at room temperature.
What it means
How much energy is that?
Per-particle units such as eV and cm⁻¹ are scaled by Avogadro’s number to become per-mole figures, so the two only match for one mole.
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Learn
Three things worth knowing
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1 eV = 96.485 kJ/mol
That is Avogadro’s number of electron volts, converted to kilojoules. And 1 kcal/mol is exactly 4.184 kJ/mol, since the calorie is defined from the joule.
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Why spectroscopists count backwards
A wavenumber in cm⁻¹ is how many wave crests fit in a centimeter, which is proportional to energy and easy to read off a grating. 1 cm⁻¹ is a tiny 0.012 kJ/mol.
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Per mole or per particle
An electron volt is one particle’s worth; a kJ/mol is a mole’s worth. Mixing them up is a factor of 6×10²³, which is the most expensive slip in chemistry.
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Background
About molar energy
Chemistry counts energy per mole, spectroscopy counts it per photon, and computational work counts it in hartrees. They describe the same jump, so a converter between them is the bridge between three literatures.
Bond energies live around 350 kJ/mol, activation energies around 80, and the thermal energy available at room temperature is only 2.5.