Sodium vapor lamps, use for public lighting, emits 489 nm yellow light. What energy is emitted by:

a) an excited sodium atom when it generates a photon?
b) 1 mole of excited sodium atoms at this wavelength?

2 answers

a.
E = hc/wavelength
E = joules/photon

b.
answer in a x 6.02E23 = energy for a mole of photons in a.
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