Thermodynamic data bases for multivalent elements: An example for ruthenium

Conference · Sun Mar 01 04:00:00 EST 1987

OSTI ID:60189

Rard, J A

Known solid anhydrous binary oxides of ruthenium are crystalline RuO{sub 2}, RuO{sub 4}, and possibly RuO{sub 3} (thin film), and known hydroxides/hydrated oxides (all amorphous) are Ru(OH){sub 3} . H{sub 2}O, RuO{sub 2} . 2H{sub 2}O, and a poorly characterized Ru(V) hydrous oxide. Although the other oxides, hydroxides, and hydrous oxides are all thermodynamically unstable with regard to RuO{sub 2}(cr) formation, they are generally obtained instead as precipitates from aqueous solutions. Characterized aqueous species of ruthenium include RuO{sub 4} (which slowly oxidizes water and which dissociates as a weak acid), RuO{sub 4}{sup -} and RuO{sub 4}{sup 2-} (which probably contain lesser amounts of RuO{sub 3}(OH){sub 2}{sup -} and RuO{sub 3}(OH){sub 2}{sup 2-}, respectively, and other species), Ru(OH){sub 2}{sup 2+}, Ru{sub 4}(OH){sub 12}{sup 4+}, Ru(OH){sub 4}, Ru{sup 3+}, Ru(OH){sup 2+}, Ru(OH){sub 2}{sup +}, Ru{sup 2+}, and some mixed valence hydroxytetramers with formal ruthenium valences of 3.75 {ge} Z {ge} 2.0. Potential-pH diagrams of the predominance regions change significantly with concentration due to polymerization/depolymerization reactions. Failure to consider the known chemistry of ruthenium can yield large differences in predicted solubilities. 87 refs., 3 figs.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 60189
• Report Number(s): UCRL--96555; CONF-870594--1; ON: DE87009135
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
AQUEOUS SOLUTIONS
CHEMICAL REACTIONS
HYDRATION
RUTHENIUM
RUTHENIUM HYDROXIDES
RUTHENIUM OXIDES
SOLUBILITY
THERMODYNAMIC PROPERTIES
WATER
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