In order to dissociate bonds, some energy input is required. this can be achieved, for instance, by using photons of a given frequency (wavelength) as energy source. assume each photon strikes one molecule, and that dissociation of a bond depends only on that photon having enough energy for the dissociation: if you have 1 mol of hcl molecules, and you have a source of 255.0 nm photons that you can use to dissociate those bonds. what is the excess energy (in ev) that a photon carries over what is needed to dissociate an h-cl bond?