Question

It takes 254 kJ/mol to eject electrons from a certain metal surface. What is the longest wavelength of
light (nm) that can be used to eject electrons from the surface of this metal via the photoelectric
effect?
I'd appreciate it if someone could explain how to do this because I have a test tomorrow and don't know where to start. Thanks!

Answer 1

254,000 J/mol x (1 mol/6.022 x 10^23) = energy/photon.

delta E = hf. h is Planck's constant, f is the frequency of the light.

Then c = f*w
c = speed of light in m/s. f is frequency in Hz, w is wavelength in meters.

Answer 2

(1.48 cg) + (0.347 g) .
Answer in units of g