Question

The energy per mole of photon of electromagnetic radiations of wavelength 4000 A

Answer 1

Explanation:

About 300 kJ/mol... How many kJ of energy would 2 mols of photons with wavelength 4000Å have?

Well, there are 10−10m in one angstrom, so 4000Å=4×10−7m. Each photon has energy

E=hν=hcλ

where:

h=6.626×10−34J⋅s is Planck's constant.

c=2.998×108m/s is the speed of light.

λ is the wavelength in m.

ν is the frequency in s−1.

Hence, the energy PER PHOTON is simply:

E=6.626×10−34J⋅s⋅2.998×108m/s4×10−7m

=4.97×10−19J/photon

But this number is clunky... since we want the MOLAR photon energy,

4.97×10−19Jphoton×6.0221413×1023photons1 mol×1 kJ1000J

= 299.07 kJ/mol