Question

Question 2.10 Electromagnetic radiation of wavelength 250 nm is just sufficient to ionise the sodium atom. Calculate the ionisation energy of sodium in kJ mol–1.
Class XI Structure of Atom Page 65

Answer 1

Explanation:

The ionization energy of sodium will be equal to the energy possessed by the radiation of wavelength 242 nm. It is E=

λ

hc

=

242×10

−9

m

6.626×10

−34

Js×3×10

8

=8.21×10

−19

J.

The ionization energy per mole is 8.21×10

−19

×6.023×10

23

=494000J=494kJ.