Vapor pressures and sublimation enthalpies of praseodymium trichloride, tribromide, and triiodide

The vapor pressures for praseodymium trihalides, PrCl3, PrBr3, and PrI3, were measured above solid and liquid phases by the torsion method. In the covered temperature ranges, their values can be expressed by the following equations: PrCl3(s), lg(p/kPa) = (12.45 +-0.20) - (16540 +- 200) K/T (from 963 to 1045 K); PrCl3(l), lg(p/kPa) = (9.56 +- 0.10) - (13422 +- 150) K/T (from 1060 to 1131 K); PrBr3(s), lg(p/kPa) = (12.06 +- 0.30) - (15060 +- 200) K/T (from 890 to 961 K); PrBr3(l), lg(p/kPa) = (9.55 +- 0.30) - (12698 +- 200) K/T (from 967 to 1061 K); PrI3(s), lg(p/kPa) = (11.31 +- 0.30) - (13766 +- 200) K/T (from 889 to 1003 K); PrI3(l), lg(p/kPa) = (8.36 +- 0.35) - (10816 +- 300) K/T (from 1013 to 1127 K). The standard sublimation enthalpies (DsubH°(298 K) = 330 +- 10, 300 +-10, and 278 +- 5 kJ mol-1 for PrCl3, PrBr3, and PrI3) respectively were determined by second- and third-law treatment of the vapor pressure data.