Posted by **Rossi** on Saturday, October 21, 2006 at 9:43am.

It takes 208.4 kJ of energy to remove 1 mole of electrons from an atom on the surface of rubidium metal. What is the maximum wavelength (in nm) of light capable of removing a single electron from an atom on the surface of rubidium metal?

Ok, I know I have to find how many kJ will be needed to remove one electron. Do I find this number by dividing 208.4kJ by 6.022 x 10^23? I have been doing it that way and I get the wrong answer. How do I find how many kJ will be needed to remove ONE electron?

Once I find the energy, I divide hc by the energy, to get lambda, right?

The is the right approach. You dont want kJ, however, you want it in Joules.

Then, use Energy=Plancksconst*speedlight/lambda

solve for lambda. You have it correct, but watch for the correct units.

Well, this is what I have done:

208.4 kJ/ 1 mol x 1 mol/ 6.0221x10^23 = 3.461x10^-22 kJ = 3.461x10^-19 J

therefore,

6.626x10^-34 x 2.9979x106^8 / 3.461x10^-19 = 5.740x10^-7m = 574.0 nm (final answer)

This is an online homework problem, and each time I submit that answer it tells me I am wrong... that is why I believe I am not doing this problem correctly. Is there an error I am making?

I dont get

* exactly you answer on Joules per electron, and it does affect the last digit of the wavelength answer. Otherwise, I dont see anything wrong.
*

I've tried with rounding to the correct sig figs throughout the problem and then not rounding to the correct sig figs until the end, and no matter what form I put, it tells me I am wrong. This is stressing... thank you though
## Answer This Question

## Related Questions

- AP chem - It takes 208.4 kJ of energy to remove 1 mole of electrons from atom on...
- Chemistry - It takes 208.4 kJ of energy to remove 1 mole of electrons from 1 ...
- Chemistry - It takes 208.4 kJ of energy to remove one mol of electrons from the ...
- Chemistry - It takes 476 kJ to remove 1 mole of electrons from the atoms at the ...
- chem - calculate the max wavelength of light capable of removing an electron for...
- AP Chemistry - To eject electrons from the surface of potassium metal, 222kJ/mol...
- Chemistry!! - Calculate the maximum wavelength of light capable of removing an ...
- Chemistry - Please help me break this problem down.. Thanks lot. Light with a ...
- Chemistry - Calculate the wavelength of light emitted when each of the following...
- chemistry - Light with a wavelength of 405 nm fell on a strontium surface, and ...

More Related Questions