Thermodynamics of Intercalation of Bromine in Graphite

Abstract

The thermodynamics of intercalation of bromine in highly oriented pyrolytic graphite had been studied by determining the pressure-temperature equilibrium diagram for stages 2–4. The standard heat and entropy of reaction for the transformation from stage n to stage n−1 (n=5, 4, 3) were found to be roughly the same, though the enthalpy of reaction became slightly more negative as the stage number increased. The heat and entropy of formation from pure graphite were thus found to be −10.9 kcal mol⁻¹ Br₂ and −30.4 cal mol⁻¹ Br₂ K⁻¹ respectively for stage 2, −11.3² kcal mol⁻¹ Br₂ and −30.6 cal mol⁻¹ Br₂ K⁻¹ respectively for stage 3, and −11.5 kcal mol⁻¹ Br₂ and −30.6 cal mol⁻¹ Br₂ K⁻¹ respectively for stage 4.