Calculating Longest Wavelength of Light to Eject Electrons

AI Thread Summary
To calculate the longest wavelength of light needed to eject electrons from a surface, one must first determine the energy required to eject a single electron from the given energy of 254 kJ/mole. This involves converting the energy from kJ/mole to joules per electron. The relationship between energy and frequency is key, as the energy of light packets (photons) is directly proportional to their frequency. Once the energy per photon is found, the wavelength can be calculated using the speed of light equation. Understanding these concepts is essential for grasping the basics of quantum mechanics.
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Please Help! (Quantum Mechanics)

I posted this in the Quantum Physics forum as well, but I ran across this one and thought it may help to put it here too. Sorry for the double post.

Hi everyone... I am new to this site. I am currently taking a major-related Chemistry course that is concentrating on quantum mechanics right now. I have been working on a homework question for about an hour now, and I am no closer to figuring it out than when I started. Something tells me that it's probably a pretty easy question, if I just knew where to begin. I need to calculate the longest wavelength (minimum frequency, right?) of light in nm that can be used to eject electrons from a surface, given that it takes 254kJ/mole. Can someone please help me!
 
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Light comes in packets. How much energy that packet has depends on the frequency. You need to find the energy it takes to eject a single electron (remember the size of a mole?) and find the frequency of light that has that amount of energy per packet (or quantum).
 
Thank you, thank you, thank you, thank you, thank you! You are a life saver! I was trying to make things way too difficult! :biggrin:
 
You can get a better understanding of Quantum Mechanics basics through OCW courses. Check out the following ocw courses from MIT and TUFTS.
http://www.opencontentonline.com/search.php?query_text=quantum+mechanics

Cheers
Trilateral
 
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