Question

Determine the energy of 1.10 mol of photons for each of the following kinds of light. (Assume three significant figures.)

Part A: infrared radiation (1490 nm )

Part B: visible light (510 nm )

Part C: ultraviolet radiation (130 nm )

Answer 1

energy of 1 photon = Plank constant *frequency
= h*c/wavelength
h= 6.626 x10^-34 js, c= 3x10^8 m/s

for IR;

E= hc/wavelength = 6.626 x10^-34 *3x10^8 m/s/1490 x10^-9 m
= 0.0133 x10^-17 J
1 mole photon =6.022 x10^23 number of photons
energy for 1. 1 mol = 0.0133 x10^-17 J* 6.022 x10^23 *1.1
= 0.0881 x10^6 j
=8.83 x10^4 J
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for visible ;
E= hc/wavelength = 6.626 x10^-34 *3x10^8 m/s/510 x10^-9 m
= 0.03897 x10^-17 J
1 mole photon =6.022 x10^23 number of photons
energy for 1. 1 mol = 0.03897 x10^-17 J* 6.022 x10^23 *1.1
= 0.258 x10^6 J
**************

for UV;
E= hc/wavelength = 6.626 x10^-34 *3x10^8 m/s/130 x10^-9 m
= 0.1529 x10^-17 J
1 mole photon =6.022 x10^23 number of photons
energy for 1. 1 mol = 0.1529 x10^-17 J* 6.022 x10^23 *1.1

= 1.01 x10^6 J
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