kJ/mol to Electronvolts Converter
Common Conversions
| kJ/mol | eV/particle |
|---|---|
| 1 | 0.01036 |
| 2.5 | 0.0259 |
| 10 | 0.1036 |
| 50 | 0.518 |
| 96.485 | 1 |
| 100 | 1.036 |
| 200 | 2.073 |
| 500 | 5.182 |
| 1000 | 10.364 |
| 1312 | 13.598 |
| 5000 | 51.82 |
Why this conversion matters in chemistry
Surface-chemistry comparisons is where this conversion shows up. The methane combustion enthalpy at −890 kJ/mol per CH₄ molecule lands at −9.22 eV per particle — the form a Ni(111) dissociative-chemisorption study reports gas-phase reaction exothermicity in. The multiplier of 0.010364 eV per kJ/mol is the inverse of 96.485, the Faraday constant in kJ/(mol · V) and exact through the 2019 SI definition of the elementary charge. It comes up when per-mole thermodynamic data ends up reported in the per-particle electronvolt form a single-molecule or single-event analysis expects.
Formula
Where the factor comes from
Strictly this is not a unit conversion, because the two sides are not the same kind of quantity: kJ/mol is an energy per amount of substance, while an electronvolt is a plain energy. Avogadro's number is what reconciles them, dividing a molar energy down to one particle's share. Taken in two steps, 1 kJ/mol ÷ (6.02214076 × 10²³ mol⁻¹) = 1.6605 × 10⁻²¹ J per particle, and dividing that by the elementary charge — exactly 1.602176634 × 10⁻¹⁹ J/eV — gives 0.0103643 eV. Both constants have been fixed since 2019, so the factor is exact. Its reciprocal is 96.485 kJ/(mol·V) — the Faraday constant, 96485.33 J/(mol·V), carrying the same prefix as the input — which is why so much of this arithmetic wears an electrochemical face.
Precision and significant figures
Five figures, 0.010364, exhausts the useful range, though the two routes to it disagree in the seventh: dividing by the full 96485.332 gives 0.01036427, while dividing by a rounded 96.485 gives 0.01036431. No measurement in chemistry can separate those. The real limits sit upstream. A DFT reaction energy is printed to meV but its accuracy against experiment is tenths of an eV; a Tauc-plot band gap is good to a few hundredths at best. Converted the other way, a formation enthalpy known to 0.1 kJ/mol yields an eV value good to about 0.001. Report the figures the measurement earned, not the ones the factor offers.
Worked Examples
The reverse anchor — the Faraday constant in kJ/(mol · V).
About the energy of a strong covalent bond per particle.
Hydrogen first ionization energy — the calibration anchor for atomic-scale energetics.
About kT at room temperature — the per-particle thermal-energy floor.
Common mistakes
The mol⁻¹ is doing the work
This factor is only legal on a per-mole quantity. Apply it to a bare kilojoule — a calorimeter reading for one specific sample, say — and the result means nothing, because nothing told the arithmetic how many particles shared the energy. Confirm the mol⁻¹ is genuinely attached before dividing by 96.485; a column headed kJ often means kJ/mol and often does not.
Per particle means per reaction as written
A tabulated ΔH is per mole of reaction with the coefficients as given. Convert the −571.6 kJ/mol for 2 H₂ + O₂ → 2 H₂O and you get −5.92 eV per reaction event, which is spread across two water molecules — so −2.96 eV per H₂O. Which of those belongs in a per-molecule comparison depends on the balanced equation, and the factor cannot decide it for you.
eV, cm⁻¹ and kelvin are separate bridges
Spectroscopy circulates several per-particle energy scales and they are not interchangeable by inspection: one eV is 8065.5 cm⁻¹ and corresponds to about 11,605 K through the Boltzmann constant, while one kJ/mol is 83.6 cm⁻¹. Convert kJ/mol to eV and then read the answer as wavenumbers and you understate it by nearly four orders of magnitude. Check which scale the source used.