ACHIEVE HW Week 2-4 #12

[Andrea_Perez_2F]

Hello, so this question is all about electron affinity. My TA said to approach this as if we are solving for a wave, I'm not too sure what this means. Can someone please explain? Thank you

[Nancy Li 1C]

I believe what your TA meant is to approach this problem as if you were solving for the energy for a typical photon. Using the wavelength given, you can find the energy of the radiation (using hc/lambda) in J and then using the reference sheet, convert to eV. The problem states that the difference between the energy of the radiation and the energy of the ejected electrons is the electron affinity, so you would subtract the energy of the ejected electrons given from the answer you just calculated and that would be the first answer. To get the second part, you would convert your electron affinity from eV to kJ and atoms to mols (using Avogadro's number).

[Rebekah Han 2K]

For this problem, my TA told me to consider the electron affinity kind of like the work function. We would use the equation E - work function = KE. To find the E, I used E=(hc)/lambda. I then converted my answer from J to eV to get the E. I then substituted the values I know, E, and the KE as given in the problem, into E - work function = KE, and I solved for the work function.

Then for the second part of the question, I converted the eV/atom to kJ/mol using Avogadro's number and the J to kJ conversion.

[405745446]

You want to use the wavelength given in order to find the energy of a photon, with the equation c = lambda(v) then use E = hv to find energy of a photon. Or you could use E = hc / lambda. Will get you the same result. The answer will be in J so make sure you convert to eV using 1ev = 1.602x10^-19J. Then subtract the energy of the photon by the energy of the ejected electrons. That'll give you electron affinity

For the second part, it's just converting. eV/atoms to kJ/mols
1eV= 1.602x10^-22kJ
Use Avogadro's number