Question

The binding energy of an electron to a metal surface is 184 kJ/mol. What is the threshold wavelength (in nm) for the onset of the photoelextric effect?

Answer 1

From the binding energy per mole, convert that to binding energy per electron (divide by avagradros number).

Then, E=h*c/lambda and solve for lambda

Answer 2

Convert 184 kJ/mol to J/atom.
184,000 x (1 mol/6.02 x 10^23 atoms) = ??J/atom.

Now delta E = hc/lambda.
You have delta E from the first calculation, you know h from one of your earlier problems, c is the speed of light in m/s; therefore, calculate lambda in meters. Then change meters to nm.
Post your work if you get stuck.