Question

These UV photons can break chemical bonds in your skin to cause sunburn—a form of radiation damage. If the 320 nm radiation provides exactly the energy to break an average chemical bond in the skin, estimate the average energy of these bonds in kj/mol.


Please provide a detail step of your methods. Thank you so very much!!!

Answer 1

In order to find the energy we first need to find the frequency of the UV photon. For it's the frequency that's the large determinate of the energy of a wave.

speed of light = (wavelength)(frequency) keep in mind we have to keep everything in units of meters

320 nm = 320 x 10^-9 m

3.0 x 10⁸ m/s = (320 x 10^-9m)(f)

f = 9.374 x 10¹⁴ s^-1

now we can use the frequency to calculate the energy related to planck's constant

E=hf

E = (6.62 x 10^-34 J-s)(9.374 x 10¹⁴ s^-1)

E = 6.21 x 10^-19 J

this is the average energy required to break one single bond. If we want to find the energy to break one mole of bonds we need to multiply by avogadro's number and also convert joules to kj.

6.21 x 10^-19 J x