Question

What is the wavelength (in meters) of photons with the following energies?

Part A.) 136 kJ/mol

Part C.) 4.55*10^-2 kJ/mol

Answer 1

A)

Given:

Energy of 1 mol = 1.36*10^2 KJ/mol

= 1.36*10^5 J/mol

Find energy of 1 photon first

Energy of 1 photon = energy of 1 mol/Avogadro's number

= 1.36*10^5/(6.022*10^23)

= 2.258*10^-19 J

This is energy of 1 photon

use:

E = h*c/lambda

2.258*10^-19J =(6.626*10^-34 J.s)*(3.0*10^8 m/s)/lambda

lambda = 8.802*10^-7 m

Answer: 8.80*10^-7 m

C)

Given:

Energy of 1 mol = 4.55*10^-2 KJ/mol

= 45.5 J/mol

Find energy of 1 photon first

Energy of 1 photon = energy of 1 mol/Avogadro's number

= 45.5/(6.022*10^23)

= 7.556*10^-23 J

This is energy of 1 photon

use:

E = h*c/lambda

7.556*10^-23J =(6.626*10^-34 J.s)*(3.0*10^8 m/s)/lambda

lambda = 2.631*10^-3 m

Answer: 2.63*10^-3 m