Calculating Longest Wavelength of Light to Eject Electrons

[chemilliterate]

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!

 

[interested_learner]

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).

 

[chemilliterate]

Thank you, thank you, thank you, thank you, thank you! You are a life saver! I was trying to make things way too difficult!

 

[trilateral]

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