Question

By using photons of specific wavelengths, chemists candissociate gaseous HI to produce H atoms with accurately knownspeeds. When HI dissociates, the H atoms move away rapidly, whereasthe relatively heavy I atoms move little. (The average bond energyof H--I is 295 kJ/mol.) (a) What is the longest wavelength (in nm)that can dissociate a molecule of HI? (b) If a photon of 200. nm isused, what is the excess energy (in J) over that needed for thedissociation? (c) If all of this excess energy is carried away bythe H atom as kinetic energy, what is its speed (in m/s)?