THE DISSOCIATION PRESSURE OF RUTHENIUM TRICHLORIDE¹

Chemistry and thermodynamics of ruthenium and some of its inorganic compounds and aqueous species

“…Shchukarev et al 162 found that residues from hightemperature decomposition pressure measurements contained only RuCl3 and Ru. Similarly, Bell et al 163 showed that chloride-deficient samples are RuC13-Ru mixtures. Thus, direct chlorination produces only RuCl3.…”

“…174 As the temperature of RuC13(c) is increased in the absence of moisture and oxygen, decomposition occurs according to reaction 32. The Cl2 pressure is about 0.02 RuC13(c) = Ru(c) + 3/2Cl2(g) (32) atm at 920 K and 1 atm at about 1145 K. 156,162,163,175,176 Sublimation (eq 33) also occurs in this temperature RuC13(c) = RuCl3(g) (33) region but is an order of magnitude less important than decomposition by reaction 32.162,176 Ru(c) is the stable solid phase above 1145 K so eq 34 occurs instead. Bell Ru(c) + 3/2Cl2(g) = RuCl3(g) (34) et al176 studied the vapor pressure above Ru(c) as a function of Cl2 pressure at 1400-1800 K. The pressure dependence indicates the dominant gaseous species is RuxC13.…”

Thermochemistry and oxidation potentials of the platinum group metals and their compounds

“…Martin (124) has also reported the following. H2RuOs(aq) = OH-(aq) + HRu04+(aq) K(20°) = 5.7 X [10][11][12][13][14][15] As a result of investigations by Silverman and Levy (187) and Connick and Hurley (45,46), we are able to give a consistent set of free energies for hydrous Ru02, Ru04-2(aq), and Ru04-(aq). Polarographic (187) and equilibrium measurements (123) in alkaline solutions have led to the following potentials.…”

“…Qi.o = 1 X [10][11][12] HOs06-(aq) = H+(aq) + 0s05"2(aq) Qi.0 ^3 X [10][11][12][13][14][15][16] Free energies of HOsOs-(aq) and 0s05-2 (aq) are calculated from these values and the tabulated AG°for H20s06(aq). The principal Os(VIII) species in 1 M OHsolution is the singly charged anion, and we calculate the following potential for Os|Os(VIII) in such solutions.…”

THE HIGH-TEMPERATURE CHEMISTRY OF FISSION-PRODUCT ELEMENTS. Summary Report, August 1, 1961-July 31, 1962

“…of the high-temperature chemistry of the chlorides of ruthenium, rhodium, and palladium have been completed and published. (2,(4)(5)(6) For . each of these metal-chlorine systems, condensed phases and vapor species were identified, di.ssociation and vapor pressures were measured, and thermodynamic data were calculated from the pressure data.…”