lodine molecule dissociates into atoms after absorbing light of `4500Å`. If one quantum of radiation is absorbed by each molecule, calculate the kinetic energy of iodine atoms. Bond energy of `I_(2)` is `240kJmol^(-1)`

Explanation

Energy of each incident photon `=(hC)/(lambda)=(6.625xx10^(-34)xx3xx10^(8))/(4500xx10^(-10)m)=9.939xx10^(-19)J`
Energy required to dissociate each `I-I` bond `=(240xx10^(3))/(6.023xx10^(23))=3.985xx10^(-19)J`
A fraction of incident light cnergy is utilised to break `I-I` bond and the remaining energy is stored in the form of kinetic energy of two iodine atoms.
Kinetic energy of each iodine atom `=(4.416xx10^(-19)-3.985xx10^(-19))/(2)=2.155xx10^(-20)J`