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### Post Assessment #28

Posted: Fri Oct 13, 2017 4:49 pm
Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 10^5 m.s^-1. The work function for sodium is 150.6 kJ.mol^-1.
How much energy is required to remove an electron from one sodium atom?

Isn't the energy required to remove the electron equivalent to the work function/threshold energy?

### Re: Post Assessment #28

Posted: Fri Oct 13, 2017 5:00 pm
yes, the energy required to remove an electron is equal to the work function or threshold energy

### Re: Post Assessment #28  [ENDORSED]

Posted: Fri Oct 13, 2017 6:30 pm
You need to divide the work function by Avogadro's number (6.022x10^23) because the it was given in kJ/mol and the question asks about the energy needed to remove one electron from ONE sodium atom, not a mole of them. I got confused on that, too! Hope this helps.

### Re: Post Assessment #28

Posted: Fri Oct 13, 2017 9:35 pm
Also be aware that the value in in kJ not just J, so you need to also do that conversion

### Re: Post Assessment #28

Posted: Sun Oct 15, 2017 2:03 pm
To answer this question you must convert the given work function from kJ to J. Then you must divide by avagadro's number to find the energy required per atom as opposed to per mole.