Photoelectric effect post-quiz 17-19  [ENDORSED]

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Ritika Saranath 3I
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Joined: Fri Sep 25, 2015 3:00 am

Photoelectric effect post-quiz 17-19

Postby Ritika Saranath 3I » Wed Oct 07, 2015 8:21 pm

Hi!

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.
A. What is the kinetic energy of the ejected electron?
B. How much energy is required to remove an electron from one sodium atom?
C. What is the frequency of the incident light on the sodium metal surface?

Since we are given the work function of sodium in the unit "kJ.mol-1", can we simply re-write 150.6 kJ.mol-1 as 150600 J, and use this value to solve parts B and C? Or since the unit also includes "mol-1", do we have to do more dimensional analysis?

Silvia Huang 3D
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Joined: Fri Sep 25, 2015 3:00 am

Re: Photoelectric effect post-quiz 17-19

Postby Silvia Huang 3D » Wed Oct 07, 2015 8:53 pm

a)

b) work energy is the energy required to remove one electron, however, this is given in moles and we want it for one sodium atom, so we divide by Avogadro's number to energy get per atom



c) the energy of the incident line = work energy + kinetic energy





hope this help :)

Helen Shi 1J
Posts: 78
Joined: Sat Jul 22, 2017 3:00 am

Re: Photoelectric effect post-quiz 17-19

Postby Helen Shi 1J » Thu Oct 12, 2017 9:40 pm

How did you get 2.5x10^-19 as the work energy?

Rachel N 1I
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Joined: Thu Jul 27, 2017 3:00 am

Re: Photoelectric effect post-quiz 17-19

Postby Rachel N 1I » Fri Oct 13, 2017 12:24 am

@Helen
In order to get the work energy, 150.6 kJ/mol must be converted to Joules (1000 kJ= 1J) and then multiplied to Avogadro's number, 6.022 x 10^23, as a conversion factor to cancel out the mol in the denominator.

RichardValdez1L
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Joined: Fri Apr 06, 2018 11:05 am

Re: Photoelectric effect post-quiz 17-19

Postby RichardValdez1L » Wed Apr 25, 2018 4:44 pm

What is an incident line and why for the second part of c. we use the E=hv equation?

Emily 1E
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Joined: Fri Apr 06, 2018 11:03 am

Re: Photoelectric effect post-quiz 17-19  [ENDORSED]

Postby Emily 1E » Sat Apr 28, 2018 12:09 pm

Incident light means the same thing as the photon used to eject the electron in this context, and E = hv is used to convert the energy of the incident light to the frequncy

805097738
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Joined: Wed Sep 18, 2019 12:20 am

Re: Photoelectric effect post-quiz 17-19

Postby 805097738 » Mon Oct 07, 2019 9:35 am

[quote="Silvia Huang 3D"]a)

how did you find m and what is m?


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