kJ/mol to eV/Atom Converter
A table gives energy per mole, but a physicist wants energy per atom. Divide by 96.485 and you get eV for one particle.
Quick answer: divide the kJ/mol by 96.485. For example, 100 kJ/mol is 1.036 eV, 436 kJ/mol is 4.519 eV and 1,000 kJ/mol is 10.364 eV.
The kJ/mol to eV per atom formula
One eV per particle is about 96.485 kJ/mol (Wikipedia: Electronvolt).
So you divide the kJ/mol by 96.48533212.
Take 100 kJ/mol. Divide by 96.485. The answer is 1.036 eV.
Take 436 kJ/mol. Divide by 96.485. The answer is 4.519 eV.
Per mole to per particle
The kJ/mol is energy for a mole of particles. The eV is energy for one (Wikipedia: Joule per mole).
One kJ/mol is about 0.0104 eV per particle (Wikipedia: Joule per mole).
The number 96.485 is the Faraday constant, in kJ per mole per volt (Wikipedia: Electronvolt).
How to convert kJ/mol to eV per atom step by step
- Write down the energy in kJ/mol.
- Divide by 96.48533212.
- The answer is in eV per particle.
- Round to the digits you need.
Example 1: 100 kJ/mol
- A typical bond is about 100 kJ/mol (Wikipedia: Joule per mole).
- 100 ÷ 96.485 = 1.036.
- The energy is 1.036 eV per particle.
100 kJ/mol = 1.036 eV
Example 2: 436 kJ/mol
- The H–H bond is about 436 kJ/mol.
- 436 ÷ 96.485 = 4.519.
- The energy is 4.519 eV per molecule.
436 kJ/mol = 4.519 eV
Example 3: 1,000 kJ/mol
- Ionization energies are about 1,000 kJ/mol (Wikipedia: Joule per mole).
- 1,000 ÷ 96.485 = 10.364.
- The energy is 10.364 eV per atom.
1,000 kJ/mol = 10.364 eV
Chemical bonds hold about 1 to 10 eV each, so about 96 to 965 kJ/mol (Wikipedia: Electronvolt).
kJ/mol to eV per atom conversion table
| kJ/mol | eV per particle | Joules per particle |
|---|---|---|
| 1 kJ/mol | 0.0104 eV | 1.6605e-21 J |
| 10 kJ/mol | 0.1036 eV | 1.6605e-20 J |
| 40.65 kJ/mol | 0.4213 eV | 6.7501e-20 J |
| 100 kJ/mol | 1.0364 eV | 1.6605e-19 J |
| 242 kJ/mol | 2.5082 eV | 4.0185e-19 J |
| 413 kJ/mol | 4.2804 eV | 6.8580e-19 J |
| 436 kJ/mol | 4.5188 eV | 7.2400e-19 J |
| 1,000 kJ/mol | 10.3643 eV | 1.6605e-18 J |
The highlighted row, 100 kJ/mol, is the default of the converter. The last column gives joules for one particle.
A quick mental shortcut for kJ/mol to eV
Divide by 100, then add 3.5 percent. So 300 kJ/mol is 3, plus a little, which is about 3.11 eV.
The exact answer is 3.109.
What eV per atom means
It is the energy of one atom or molecule, in electronvolts (Wikipedia: Electronvolt).
Physics papers on materials use it.
What kJ/mol means
It is the energy of one mole of particles (Wikipedia: Joule per mole).
Chemistry data tables use it.
Atom or molecule
The same maths works for atoms, molecules and ions. The unit just says per particle.
Always say what the particle is.
Why divide by 96.485
A mole is 6.022 × 10²³ particles. One eV times that many is 96.485 kJ.
So the move from molar to single goes down by 96.485.
Band gaps
Materials science lists band gaps in eV. A gap of 1.12 eV is 108 kJ/mol.
Use the eV to kJ/mol converter for that.
Photons
A photon of 1.04 eV, about 1,190 nm, carries 100 kJ/mol if you absorb a mole of them (Wikipedia: Electronvolt).
That is near-infrared light.
Thermal energy
At 20 °C, kT is about 0.025 eV (Wikipedia: Electronvolt). That is 2.4 kJ/mol.
A 100 kJ/mol bond is about 40 kT.
eV back to kJ/mol
To go back, multiply the eV by 96.485.
So 1.036 eV is 100 kJ/mol.
Check your answer
Multiply your eV answer by 96.485. You should get your starting kJ/mol.
The eV number should be about 100 times smaller.
More values at a glance
1 kJ/mol is 0.010364 eV, 10 kJ/mol is 0.10364 eV and 50 kJ/mol is 0.51821 eV.
96.485 kJ/mol is 1 eV, 100 kJ/mol is 1.0364 eV and 200 kJ/mol is 2.0729 eV.
500 kJ/mol is 5.1821 eV, and 1,000 kJ/mol is 10.364 eV.
The unit sizes
One eV per particle is about 96.485 kJ/mol. So divide the kJ/mol by 96.485.
If a result looks very large or very small, compare it with these sizes before you use it.
Checking in reverse
Convert 0.51821 eV back to kJ/mol. You should get 50 kJ/mol.
A bond example
A C–H bond near 413 kJ/mol is about 4.28 eV per bond. A bond of 100 kJ/mol is about 1.04 eV.
Quick conversion answers
| Conversion | Result |
|---|---|
| 1 kJ/mol to eV | 0.0104 eV |
| 10 kJ/mol to eV | 0.1036 eV |
| 40.65 kJ/mol to eV | 0.4213 eV |
| 100 kJ/mol to eV | 1.0364 eV |
| 436 kJ/mol to eV | 4.5188 eV |
| 1,000 kJ/mol to eV | 10.3643 eV |
Where this conversion is used
Materials scientists compare chemistry tables with band gaps.
Physics students link molar and single-particle energy.
Chemists compare bond strength with photon energy.
Common mistakes to avoid
- Multiplying by 96.485. That goes the wrong way.
- Forgetting the 1,000. The formula uses J, not kJ.
- Using eV for a mole. The eV is per particle.
- Mixing eV and meV. A meV is one thousandth of an eV.
Related converters
A bond example
A bond of 436 kJ/mol breaks with 4.52 eV for each molecule.
A photon of that energy has a wavelength of about 274 nm, which is ultraviolet.
A vaporization example
Water needs 40.65 kJ/mol to vaporize. That is 0.421 eV for each molecule.
It is far below a covalent bond.
A band gap example
A material with a gap of 1.12 eV has 108 kJ/mol. If you only know 108 kJ/mol, divide by 96.485 to get 1.12 eV back.
It is a handy way to cross check.
Frequently asked questions
How do I convert kJ/mol to eV?
Divide the kJ/mol by 96.485.
How many eV is 100 kJ/mol?
About 1.036 eV per particle.
How many eV is 1 kJ/mol?
About 0.0104 eV.
Is the eV per atom or per mole?
Per atom, molecule or other single particle.
Why 96.485?
It is the Faraday constant in kJ per mole per volt.
How many eV is 1,000 kJ/mol?
About 10.36 eV.
Sources
- Wikipedia: Electronvolt (en.wikipedia.org)
- Wikipedia: Joule per mole (en.wikipedia.org)
