Determine the energy of 1.80 mol of photons for each of the following kinds of light. (Assume three significant figures.)

Question

Determine the energy of 1.80 molmol of photons for each of the following kinds of light. (Assume three significant figures.)

infrared radiation (2490 nmnm ) =

visible light (480 nmnm ) =

ultraviolet radiation (150 nmnm ) =

Answer 1

I'll do the first one. You can use the same process to do the other 2.

Infrared radiation (2490 nm)

The energy of 1 photon = E = hc/λ where h = Planck's constant (6.626x10^-34 Jsec); c = speed of light (3x10⁸ m/sec) and λ = wavelength (2490 nm = 2.490x10^-6 m)

E = (6.626x10^-34 Jsec)((3x10⁸ m/sec) / 2.490x10^-6 m

E = 7.98x10^-20 J This is the energy from 1 photon

E from 1 mole of photons = 7.98x10^-20 J / photon x 6.022x10²³ photons / mol = 48056 J / mol

E from 1.80 mols of photons = 48056 J / mol x 1.80 mol = 86,500 J = 86.5 kJ (3 sig. figs.)

Do the others the same way but only need to change λ and be sure to convert λ to m instead of nm