Mass Spectrometric Study of the Vaporization of Cuprous Chloride and the Dissociation Energy of Cu3Cl3, Cu4Cl4, and Cu5Cl5

The vapor phase in equilibrium with cuprous chloride has been studied using the Knudsen effusion‐mass spectrometric technique. The polymeric species Cu₃Cl₃, Cu₄Cl₄, and Cu₅Cl₅ were observed, the first two in comparable amounts. Partial pressures and heats of vaporization for each species were measured: $$\text{3\hspace{0.17em}}\mathrm{CuCl}(\mathrm{s}\mathrm{)\to }{\mathrm{Cu}}_3{\mathrm{Cl}}_3(\mathrm{g}{\mathrm{),\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\Delta \; H}}_{640}^{\mathrm{o}}\text{=33.7± 0.8\hspace{0.17em}}\mathrm{kcal}/\mathrm{mole},$$ $$\text{4\hspace{0.17em}}\mathrm{CuCl}(\mathrm{s}\mathrm{)\to }{\mathrm{Cu}}_4{\mathrm{Cl}}_4(\mathrm{g}{\mathrm{),\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\Delta \; H}}_{650}^{\mathrm{o}}\text{=34.6± 0.7\hspace{0.17em}}\mathrm{kcal}/\mathrm{mole},$$ $$\text{5\hspace{0.17em}}\mathrm{CuCl}(\mathrm{s}\mathrm{)\to }{\mathrm{Cu}}_5{\mathrm{Cl}}_5(\mathrm{g}{\mathrm{),\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\Delta \; H}}_{665}^{\mathrm{o}}\text{=41± 1\hspace{0.17em}}\mathrm{kcal}/\mathrm{mole}.$$ The atomization energies for these molecules calculated on the basis of the Rittner ionic model are compared with the experimental values.