Sodium metal surface

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Madison Gil 3D
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Sodium metal surface

Postby Madison Gil 3D » Sun Oct 14, 2018 6:09 pm

Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1.
I got the KE of the ejected electron as 1.99 x 10^-19.
How much energy is required to remove an electron from one sodium atom?
and
What is the frequency of the incident light on the sodium metal surface?
Thank you.

Chem_Mod
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Re: Sodium metal surface

Postby Chem_Mod » Sun Oct 14, 2018 6:25 pm

The first thing you should think about: What is the definition of work function?

Second: Conservation of Energy. The energy required to remove an electron from the surface + the electron's kinetic energy should be equal to the energy that was introduced to the system (the energy of the incident light)

Madison Gil 3D
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Re: Sodium metal surface

Postby Madison Gil 3D » Sun Oct 14, 2018 6:44 pm

For the work function, I got 1.506 x 10^5 J, but on the post assessment survey for photoelectric effect, the answer showed up as wrong.
Would the frequency be (1.99 x 10^-19)/(6.626 x 10^-34) = 3.01 x 10^-14 Hz?

Michael Torres 4I
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Re: Sodium metal surface

Postby Michael Torres 4I » Sun Oct 14, 2018 7:45 pm

Madison Gil 3D wrote:For the work function, I got 1.506 x 10^5 J, but on the post assessment survey for photoelectric effect, the answer showed up as wrong.
Would the frequency be (1.99 x 10^-19)/(6.626 x 10^-34) = 3.01 x 10^-14 Hz?


I'm not sure about your first question.

However, for your second question consider the fact that (Planck's constant)(frequency) = (work function) + (kinetic energy).

Therefore the frequency should be (frequency) = ((work function) + (kinetic energy))/(Planck's constant).

Alli Hinmon 3E
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Re: Sodium metal surface

Postby Alli Hinmon 3E » Sun Oct 14, 2018 8:28 pm

I made sure to state the conservation of energy. E (removal of e) + KE = Total energy of the system (Incident Light)


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