2011-03-09, 11:52 AM
Ohhhhhhhhhhhhhhhhhhhhhhhhhhh I didn't notice the atom/mole thing...
Okay first of all convert Energy to J/atom.
So 2372 kJ/mol = 3272000 J/mol.
To convert to J/atom divide by Avogadro's number (6.022E23)
So the total energy for an electron to leave an atom of Helium is 3.93E-18.
Since it's already in the second energy level (2p) we subtract our 3.4E-18 from 3.95E-18, and get that it needs 5.388E-19 Joules of energy more for the electron to get out of the Helium.
Plug that number into your formula E=hc/wavelength and you should get the same answer in the book, 3.68E-7 meters.
And in hindsight, since we used the number from A in question B, and it worked out perfectly to get the answer in B, then our answer to question A was right and your book has a typo.
Okay first of all convert Energy to J/atom.
So 2372 kJ/mol = 3272000 J/mol.
To convert to J/atom divide by Avogadro's number (6.022E23)
So the total energy for an electron to leave an atom of Helium is 3.93E-18.
Since it's already in the second energy level (2p) we subtract our 3.4E-18 from 3.95E-18, and get that it needs 5.388E-19 Joules of energy more for the electron to get out of the Helium.
Plug that number into your formula E=hc/wavelength and you should get the same answer in the book, 3.68E-7 meters.
And in hindsight, since we used the number from A in question B, and it worked out perfectly to get the answer in B, then our answer to question A was right and your book has a typo.