Problem 6.29 One type of sunburn occurs on exposure to UV light of wavelength in
ID: 909921 • Letter: P
Question
Problem 6.29
One type of sunburn occurs on exposure to UV light of wavelength in the vicinity of 300 nm .
Part A
What is the energy of a photon of this wavelength?
6.6•109
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Part B
What is the energy of a mole of these photons?
4•1015
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Part C
How many photons are in a 1.10 mJ burst of this radiation?
179487
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Part D
These UV photons can break chemical bonds in your skin to cause sunburn—a form of radiation damage. If the 300 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.
3.99•1012
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Problem 6.29
One type of sunburn occurs on exposure to UV light of wavelength in the vicinity of 300 nm .
Part A
What is the energy of a photon of this wavelength?
E =6.6•109
JSubmitMy AnswersGive Up
Incorrect; Try Again; 2 attempts remaining
Part B
What is the energy of a mole of these photons?
E =4•1015
JSubmitMy AnswersGive Up
Incorrect; Try Again; 4 attempts remaining
Part C
How many photons are in a 1.10 mJ burst of this radiation?
N =179487
photonsSubmitMy AnswersGive Up
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Part D
These UV photons can break chemical bonds in your skin to cause sunburn—a form of radiation damage. If the 300 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.
averagebondenergy =3.99•1012
kJ/molSubmitMy AnswersGive Up
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Explanation / Answer
WL = 300 nm
A)
Energy
E = hc/WL
h = 6.626*10^-34 planck constant
c = 3*10^8 m/s speed of light
E = (6.626*10^-34)(3*10^8) / (300*10^-9) = 6.626e*10^-19
B)
Energy of 1 mol of photon
E = 6.626e*10^-19 * 6.022*10^23 = 1084642.61751 J
C)
if E = 1.1 *10^-3 J
find numebr of photons
6.626e*10^-19 J/e-
then
#photon = (1.1 *10^-3 J)/(6.626e*10^-19 J/p) = 1.66*10-15 photons