Question

What is the energy per mole of photons of light with a wavelength of 812.4 nm? a.) 2.45 x 10^-19 KJ/mol b.) 1.47 x 10^2 KJ/mol c.)4.89 x 10^14 KJ/mol d.) 2.22 x 10^35 KJ/mol e.) 3.69 x10^14 KJ/mol (please show work)

Answer 1

First calculate energy per photon

E = hc / where,

E = energy per photon

h = Planck constant = 6.62610^-34J s

c = velocity of light = 3.0010⁸ m/s

= 812.4 nm = 812.4 10^-9 m

Substitute value

E = (6.62610^-34)(3.0010⁸) / (812.4 10^-9)

E = 2.44682 10^-19J it is energy of one photon

in 1 mole contain 6.022 10²³ photon

then energy of 6.022 10²³ photon =  2.44682 10^-19J 6.022 10²³

= 1.47 10⁵J = 1.47 10² KJ

Answer - b) 1.47 10² KJ/mol