Threshold Energy Question

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305154707
Posts: 31
Joined: Fri Sep 28, 2018 12:16 am

Threshold Energy Question

Postby 305154707 » Wed Oct 10, 2018 5:17 pm

This problem gives the work function for sodium as 150.6 kJmol-1. Then, in the following part of the question, it asks for the energy required to remove an electron from one sodium atom. Given that the work function is the same as the " energy required to remove an electron", why can't I just convert 150.6kJmol-1 to 1.506 x 10^5J? What else do I do? Thanks.
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Lorena Zhang 4E
Posts: 63
Joined: Fri Sep 28, 2018 12:16 am

Re: Threshold Energy Question

Postby Lorena Zhang 4E » Wed Oct 10, 2018 6:13 pm

This problem is asking for the energy required to remove an electron from ONE sodium atom. The work function given is the threshold energy needed to remove the electron from one mole of sodium atom. Therefore, in order to get the energy required to remove an electron from one sodium atom, you need to divide the work function by 6.022*10^23.

Andonios Karas 4H
Posts: 30
Joined: Fri Sep 28, 2018 12:27 am

Re: Threshold Energy Question

Postby Andonios Karas 4H » Wed Oct 10, 2018 6:17 pm

You are correct the work function is the energy need to remove one electron. However the number provided to you is in kiloJoules per Mole. The problem is asking for the J per Atom. You need to divide by Avogadro's number (6.022 x 10^23) and multiply by 1000 Joules in order to get the joules per one atom of sodium.


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