##### how much energy in kJ do 3 moles of photons, all with a wavelength of 655 nm

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Apr 6th, 2015

Use ν = c / λ to get the frequency:

x = (3.00 x 108 m s¯1) / (655 x 10¯9 m)
= .004580*  x 10171.

Now use E = hν to get the energy:

x = (6.6260755 x 10¯34 J s) (.004580*  x 10171.)
= .030348 x 10¯17 J

This is the energy for one photon

The next step is to find the kilojoules for one mole and for this we use Avogadro's Number
(.030348 x 10¯17 J/photon) (6.022 x 1023 photon mol¯1)

= .182755 * 106

Dividing the answer by 1000 to make the change to kilojoules, we get 182.755 kJ/mol.

The last step is to find the kilojoules for 3 moles ,

that is 3 x 182.755

= 548.265 KJ

So the correct answer is D: 548KJ

Please let me know if it is helpful and best me if you are satisfactory.

Apr 6th, 2015

hi,

Please let me know if you have any other questions

Apr 6th, 2015

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Apr 6th, 2015
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Apr 6th, 2015
Oct 17th, 2017
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