"Work Function" (from Post-Assessment Module)

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Chloe Alviz 1E
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"Work Function" (from Post-Assessment Module)

Postby Chloe Alviz 1E » Thu Oct 10, 2019 4:41 pm

My question refers to a problem from the post-assessment module:

"Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 10^5 ms-1. The work function for sodium is 150.6 kJ mol-1...."

In this question, what does the "work function" refer to? Is it supposed to be the threshold energy?

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Re: "Work Function" (from Post-Assessment Module)

Postby Chem_Mod » Thu Oct 10, 2019 4:56 pm

Work function (kJ/mol) is the energy needed to eject one mole of e- from the metal surface.

Light is hitting the sodium metal, and ejected e- have a specified velocity, indicating it has kinetic energy. The energy of the incoming light is used to eject e- (work function), and any leftover energy goes towards kinetic energy.

Jocelyn Thorp 1A
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Re: "Work Function" (from Post-Assessment Module)

Postby Jocelyn Thorp 1A » Thu Oct 10, 2019 5:05 pm

Chem_Mod answered your question already but if you want the equation it's used in, here you go

The work function is the Φ in the equation that relates the kinetic energy of the ejected electron to the energy supplied by a photon and the work function.

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Re: "Work Function" (from Post-Assessment Module)

Postby 005206171 » Thu Oct 10, 2019 8:25 pm

In the context of the photoelectric effect and experiment, the work functions describe the minimum energy a photon needs to knock off an electron so that the electron can overcome it's an attraction to the plate. Some electrons are more attracted to the metal than others. Those with the highest max kinetic energy will have to use the least amount of energy from the photon to pop off the metal.

Shrayes Raman
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Re: "Work Function" (from Post-Assessment Module)

Postby Shrayes Raman » Fri Oct 11, 2019 8:44 am

The work function refers to the energy required to eject an electron. This is subtracted from the initial energy of the incoming photon to find the energy of the photon as it leaves

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