Question

Determine the energy of 2.00 mol of photons for each of the following kinds of light. (Assume three significant figures.)

Infrared radiation (1590nm)

Visible light (500nm)

UV radiation (150nm)

Answer 1

Useful formulas are
Energy of a photon E = hc/λ joules
where h is plank's constant = 6.626 x10^-34 Js,
c= speed of light = 3 x10^8 m/s
λ = wavelength in meters

Energy of 1 mol photon = [hc/λ ]*6.022 x10^23 joules
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Infrared radiation (1590nm)

Energy of a photon E = hc/λ joules where λ= 1590 x10^-9 m

  
Energy of 1 mol photon = [hc/λ ]*6.022 x10^23 joules
= 6.626 x10^-34 Js*3 x10^8 m/s 6.022 x10^23 /1590 x10^-9 m
= 0.07528 x10^6 J
energy of 2 mol photon = 2* 0.07528 x10^6 j
= 0.151 x10^6 J
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Visible light (500nm)
Energy of a photon E = hc/λ joules where λ= 500 x10^-9 m

  
Energy of 1 mol photon = [hc/λ ]*6.022 x10^23 joules
= 6.626 x10^-34 Js*3 x10^8 m/s 6.022 x10^23 /500 x10^-9 m
= 0.239 x10^6 J
energy of 2 mol photon = 2* 0.239 x10^6 j
= 0.478 x10^6 J
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UV radiation (150nm)

Energy of a photon E = hc/λ joules where λ= 150 x10^-9 m

  
Energy of 1 mol photon = [hc/λ ]*6.022 x10^23 joules
= 6.626 x10^-34 Js*3 x10^8 m/s 6.022 x10^23 /150 x10^-9 m
= 0.798 x10^6 J
energy of 2 mol photon = 2* 0.798 x10^6 j
= 1.60x10^6 J
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