The energy required to dislodge electrons from sodium metal via the photoelectric effect is 275 kJ/mol What wavelength in m of light has sufficient energy to dislodge an electron from the surface of sodium?

1 Answer
Gió
Nov 2, 2016

I got #430nm#

Explanation:

You need #275kJ# to dislodge one mol of electrons so we need:

#(275xx10^3)/(6xx10^23)=4.6xx10^-19J# for one electron only.

We can use Einstein`s relationship between energy #E# and frequency #f# and between frequency and wavelength #lambda#:

#E=hf=hc/lambda#

to find the wavelength (#h# is Plank`s Constant and #c# the speed of light).
We get:
#lambda=hc/E=(6.6xx10^-34)*(3xx10^8)/(4.6xx10^-19)=4.3xx10^-7m=430nm#

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