Chemistry problem help please?

Question

A mol of photon in the red visible region of the electromagnetic spectrum has an energy of 181 kj/mol

calculate the wavelength in nm of the photons


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I have a solution but i dont understand it. i guess im supposed to change kj/mol to j/photon, why? how?

Answer 1

1 Mol (of photons, electrons, atoms, molecules, ions, etc) is 6.022x10^23 pieces (of photons, electrons, atoms, molecules, ions, etc). Thus, to convert kj/mol to j/photon is easy:
1 kj/Mol = 1000 j/Mol = {1000/(6.022x10^23)} J/photon.
Why? Because the wavelength in nm to be calculated is of the photons, not Moles.