plz explain step byu step?

Question

If a certain source emits radiation of wavelength 320. nm what is the energy, in kJ, of one mole of photons of this radiation?

Answer 1

First you need the Energy of 1 Photon-:

E = h f = hc / lambda (as c = f lambda)

6.63 x 10^-34 x 3 x 10^8 / 320 x10^-9

= 6.215625 x 10^-19 Joules

Now we multiply by Avagadro's Number (the number of atoms in 1 mole.)

6.215625 x 10^-19 x 6.023 x 10^23 = 374367.0938 Joules

Now to convert to K Joules we have to divide by 1000.

374367.0938 / 1000 = 374.367 K Joules