Question

One type of sunburn occurs on exposure to UV light of wavelength in the vicinity of 325 nm. (a) What is the energy of a photon of this wavelength? (b) What is the energy of a mole of these photons? (c) How many photons are in a 1.00 mJ burst of this radiation? (d) These UV photons can break chemical bonds in your skin to cause sunburn—a form of radiation damage. If the 325-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.

b) 1 mole of photons has Avogadro’s number of photons. Energy of 1 mole of photons is:

c) Number of photons in 1 mJ of radiation is calculated by dividing total energy with the energy of one photon:

d) Average energy of chemical bonds (in human skin equals the energy of photons with 325 nm wavelength, which is already calculated to be 3.68×10­⁵ J/mol which is 368 kJ/mol.