When H-I dissociates, the H atoms move away rapidly, whereas the relatively heavy I atoms move little. By using photons of specific wavelengths, chemists can dissociate gaseous H-I to produce H atoms with accurately known speeds.
1. Calculate the longest wavelength that can dissociate a molecule of H-I?
2. Determine the excess energy over that needed for the dissociation if a photon of 217 nm is used.