The energy required to eject an electron from sodium metal via the photoelectric effect is 275 kJ/mol. What wavelength (in nm) of light has enough energy per photon to eject an electron from the surface of sodium?

I would like a hint please.

Question

The energy required to eject an electron from sodium metal via the photoelectric effect is 275 kJ/mol. What wavelength (in nm) of light has enough energy per photon to eject an electron from the surface of sodium?

I would like a hint please.

anonymous · Answer

I haven't done a problme like this one but I think the following formulas may help. Issue I see is getting that 275kJ / mol in straight energy form. Someone else can help with that I'm sure.

$$f=\frac{c}{\lambda}$$ where lamba is wavelength, c is speed of light and f is frequency.
$$E=\frac{hc}{\lambda}$$
h is Planck's constant. You'll need it in a value that matches your units.

anonymous · Answer

I think you probably need to just assume that you have one electron being ejected so take your 275kJ/mol and multiply it by (1mol/6.022x10^23) so you have the energy for one electron. I think you can then use the energy you solve for and plug that into the second formula $$E=(hc)/\lambda$$ and solve for lambda.