Vaporization study of samarium trichloride, samarium tribromide and samarium diiodide

The vapor pressures of solid (s) and liquid (l) SmCl3, SmBr3 and SmI2 were measured by torsion method and the following selected equations were derived in the temperature ranges studied, SmCl3(s): log p=(11.56±0.30)-(14,950±300)/T (895-941 K), SmCl3(l): log p=(7.88±0.10)-(11,530±100)/T (953-1077 K), SmBr3(s): log p=(11.87±0.30)-(14,470±250)/T (844-925 K), SmBr3(l): log p=(9.73±0.10)-(12,550±100)/T (950-1039 K), SmI2(l): log p=(8.10±0.10)-(12,370±200)/T (1032-1210 K). Treating by the second-law method the obtained data, the following standard sublimation enthalpies at 298 K were determined: 305±10, 292±10 and 272±10 kJ mol-1 for SmCl3, SmBr3 and SmI2, respectively. The sublimation enthalpy value for SmCl3 was also obtained from the third-law treatment of the vapor pressure.