# How would I calculate the energy (in kilojoules) for 1 mole of a photon having a wavelength of 623nm? If I first calculated the energy of the photon in Joules and got 3.20x10^-37J.

##
I am wondering if I would need to find out the wavelength of 1 mole of these photons first and then carry out the same steps as I did when looking for the energy of the single photon. So:

if I converted nm to m first, then: 6.23x10^11m X 6.022x10^23 = *_*____m

and plug that into my E= h * c/wavelength = *_**_*___ and convert that to kilojoules?

I am wondering if I would need to find out the wavelength of 1 mole of these photons first and then carry out the same steps as I did when looking for the energy of the single photon. So:

if I converted nm to m first, then: 6.23x10^11m X 6.022x10^23 = ** _**____m

and plug that into my E= h * c/wavelength = *_*** _**___ and convert that to kilojoules?

##### 1 Answer

#### Answer:

Your methodology, although not executed, seems sound. However,

#### Explanation:

Consider,

Moreover, consider the frequency of one photon at that wavelength,

Now, recall,

The energy for **one photon** of that wavelength is then,

Hence,

of energy are in that many photons of that wavelength.