"The sun emits UV radiation that can have serious health consequences. In particular, so-called UVB radiation is mostly absorbed by the ozone layer in the upper atmosphere (altitudes of 10 - 50 km), but the part that reaches the earth can cause DNA mutations. The highest energy UVB photons have a wavelength of 320 nm. Calculate the energy of a single UVB photon (in Joules) and the energy of one mole of UVB photons (in kJ/mol)."

Question

"The sun emits UV radiation that can have serious health consequences. In particular, so-called UVB radiation is mostly absorbed by the ozone layer in the upper atmosphere (altitudes of 10 - 50 km), but the part that reaches the earth can cause DNA mutations. The highest energy UVB photons have a wavelength of 320 nm. Calculate the energy of a single UVB photon (in Joules) and the energy of one mole of UVB photons (in kJ/mol)."

So, I'm pretty sure the first part of the question is unnecessary info. I think that I can calculate the energy in Joules by using E=hc/320nm. For that I'm getting 6.21 x 10^-19 J. I just need help finding the energy of one mole of UVB photons. Do just multiply my answer by Avogadro's number?

An explanation would be awesome, thanks in advance!

Answer 1

I worked this prolem for you last night. Go back to your post yesterday and look for the answer.

Answer 2

http://www.jiskha.com/display.cgi?id=1347592788

Answer 3

You're on the right track! To find the energy of one mole of UVB photons, you can indeed multiply your answer for the energy of a single UVB photon by Avogadro's number.

Avogadro's number, denoted as Nₐ, is approximately equal to 6.022 x 10²³. It represents the number of particles (atoms, molecules, or in this case, photons) in one mole of a substance.

Since you have already calculated the energy of a single UVB photon as 6.21 x 10⁻¹⁹ J, you can now find the energy of one mole of UVB photons in Joules by performing the multiplication:

Energy of one mole of UVB photons (in J) = (6.21 x 10⁻¹⁹ J) x (6.022 x 10²³)

Performing the multiplication gives you the energy of one mole of UVB photons in Joules. However, the result might be in very small units due to the small value of the constant for a single photon. In this case, it's more convenient to express the answer in kilojoules (kJ).

To convert from joules to kilojoules, simply divide the obtained value by 1000:

Energy of one mole of UVB photons (in kJ/mol) = (Energy of one mole of UVB photons in J) / 1000

The final result will give you the energy of one mole of UVB photons in kilojoules.