Low-Temperature Heat Capacities and Derived Thermodynamic Functions of Para-Substituted Halogen Benzenes. 2. p-Bromoiodobenzene and p-Diiodobenzene

Heat capacity measurements were made on p-bromoiodobenzene and p-diiodobenzene from 5 K to 380 K and from 5 K to 420 K, respectively. The measurements were used to calculate the entropy and enthalpy values relative to 0 K. The enthalpy of melting of p-bromoiodobenzene was found to be (19375 ± 20) J·mol-1, and the triple-point temperature, (363.52 ± 0.01) K. For p-diiodobenzene these values were respectively (22328 ± 50) J·mol-1 and (402.40 ± 0.05) K. A small solid−solid transition occurs in p-diiodobenzene. The maximum of this transition was measured at 327 K for sublimated material and shifted to 322 K for crystallized material. The enthalpy of transition was found to be (223 ± 10) J·mol-1.