A light emitting diode (L.E.D.) emits photons with an energy of #2.84 xx 10^-19# J. What is the energy per mole of photons emitted?

1 Answer
Dec 29, 2017


The molar energy of the photons is 171 kJ/mol.


Just as a dozen is twelve of anything, so a mole is Avogadro's number = #6.02×10^{23}# of anything. So the energy of the given light beams may be rendered as


This is similar in magnitude to the energy involved in chemical reactions, accounting for the fact that light often drives chemical reactions. One real-world example of this is given in https://en.wikipedia.org/wiki/Photosynthesis.