The Thermal Dissociation of Cyanogen into Cyanide Radicals

The thermal dissociation of cyanogen into cyanide radicals around 1200°C has been studied. Determining the variation of CN concentration with temperature by the intensity of absorption bands, the heat of dissociation 77±4 kg cal. has been obtained. With this quantity the heat of dissociation of hydrogen cyanide into hydrogen atoms and cyanide radicals is calculated as 94.5±4 kg cal. By the use of existing thermochemical data these quantities are shown to be the most probable values for the energies of the C–C and C–H bonds, respectively. The heat of sublimation of carbon is calculated as 154±3 kg cal.