Difference Between Work Function and the Energy Required to Remove an Electron from one Atom  [ENDORSED]

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Caroline C 1G
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Difference Between Work Function and the Energy Required to Remove an Electron from one Atom

Postby Caroline C 1G » Fri Oct 13, 2017 3:46 pm

One of the questions in the "Photoelectric Effect" post module assessment included, "How much energy is required to remove an electron from one sodium atom?" The statements before the question disclosed that the work function of sodium is 150.6 kJ/mol. I assumed that the question was simply asking for the work function, so I chose the option "1.506 x 10^5 J". However, my answer was incorrect. What is the difference between the work function of an element and the amount of energy needed to remove an electron from one atom of the element? How do you calculate this energy?

Mitch Mologne 1A
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Re: Difference Between Work Function and the Energy Required to Remove an Electron from one Atom  [ENDORSED]

Postby Mitch Mologne 1A » Fri Oct 13, 2017 5:34 pm

The question asked for the energy for a single atom, not for a mole of sodium, while the work function was given in KJ/mol. In order to find the energy for a singular atom, divide the work function by Avogadro's number (6.022* 10^23)

Nora 1F
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Re: Difference Between Work Function and the Energy Required to Remove an Electron from one Atom

Postby Nora 1F » Sun Oct 15, 2017 10:26 pm

So to clarify, you are correct in thinking that the work function is equivalent to the energy needed to remove an electron from one atom of an element. This is also referred to as threshold energy. To go back to the equation, the total energy of the photon will be equal to the work function plus the kinetic energy of the electron that is removed.

E (photon) = work function + KE

Akash_Kapoor_1L
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Re: Difference Between Work Function and the Energy Required to Remove an Electron from one Atom

Postby Akash_Kapoor_1L » Tue Oct 17, 2017 1:28 am

The only thing that you forgot was the stoichiometry, you need to convert the given data from kg/mol to J/atom ... Otherwise you are correct because the Work Function is defined as the Energy Required to Remove an Electron.

Gobinder Pandher 3J
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Joined: Fri Sep 29, 2017 7:07 am

Re: Difference Between Work Function and the Energy Required to Remove an Electron from one Atom

Postby Gobinder Pandher 3J » Sun Oct 22, 2017 10:09 pm

I agree with MitchellMologne. Although subtle, the question did ask for the energy of a single atom. A great way to tell if you need to calculate energy for a single atom is to look at the units they give for the work function. In this case it was KJ/mol. The "mol" aspect can be an indicator that you may need to calculate energy for a single atom. I hope this helps!


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