rhodium

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rhodium

(rō`dēəm), metallic chemical element; symbol Rh; at. no. 45; at. wt. 102.90550; m.p. about 1,966°C;; b.p. 3,727±100°C;; sp. gr. 12.41 at 20°C;; valence +2, +3, +4, +5, or +6. Rhodium is a lustrous, silver-white, chemically resistant metal in the so-called platinum group of metals in Group 9 of the periodic tableperiodic table,
chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled
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. It has a face-centered cubic crystalline structure. It is insoluble in most acids, including aqua regia, but is dissolved in hot concentrated sulfuric acid. Rhodium compounds include halides, oxides, sulfates, sulfites, a nitrate, and a sulfide. The salts form rose-colored aqueous solutions. Rhodium is found associated with other platinum metals in river sands and in compounds in such minerals as rhodite and sperrylite. It is obtained as a byproduct in the refining of nickel sulfide ores mined near Sudbury, Ont., Canada.

The major use of the metal is in alloys with platinum and iridium; it gives improved high-temperature strength and oxidation resistance. These alloys are used in pen nibs, high-temperature thermocouple and resistance wires, bearings, and electrical contacts and as a catalyst. In motor vehicle catalytic converters, it converts the nitrogen oxides in the exhaust into nitrogen and oxygen. The metal itself, because of its brilliance and resistance to tarnish, is used to plate jewelry and the reflectors of searchlights. Rhodium was discovered in 1804 by W. H. WollastonWollaston, William Hyde,
1766–1828, English scientist, M.D. Cambridge, 1793. His wide-ranging scientific achievements include the discovery (1802) of the dark lines (Fraunhofer lines) in the solar spectrum; invention of the reflecting goniometer (an instrument by which the
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 in crude platinum ore.

rhodium

[′rōd·ē·əm]
(chemistry)
A chemical element, symbol Rh, atomic number 45, atomic weight 102.9055.
(metallurgy)
A silver-white metal in the platinum family; sometimes alloyed with platinum for thermocouples or used as a tarnish-resistant electrode posit.

rhodium

a hard corrosion-resistant silvery-white element of the platinum metal group, occurring free with other platinum metals in alluvial deposits and in nickel ores. It is used as an alloying agent to harden platinum and palladium. Symbol: Rh; atomic no.: 45; atomic wt.: 102.90550; valency: 2--6; relative density: 12.41; melting pt.: 1963?3?C; boiling pt.: 3697?100?C
References in periodicals archive ?
CONTACT: John Arthur or Tom Arnold, 33-72-85-24-75 or 33-72-85-24-74, of Rhone-Poulenc Rhodic, or Beverley Miles of Rhone-Poulenc, 33-47-68-09-79/
Rauber LP, Piccolla CD, Andrade AP, Friederichs A, Mafia AL, Correa JC, Albuquerque JA (2012) Physical properties and organic carbon content of a Rhodic Kandiudox fertilized with pig slurry and poultry litter.
Stress of 3200 kPa applied on the Rhodic Paleudalf and Rhodic Hapludox, both for the compression curve and for the single stress, increased the bulk density when compared with the 1600kPa stress (Fig.
The deep, well-drained soil is classified as a clayey, kaolinitic Rhodic Ferralsol in the FAO System (FAO 2006) and as Latosssolo Vermelho distrofrrrico in the Brazilian Soil Classification System (EMBRAPA 2006).
For the Rhodic Kandiudult, Nkometou and Etoud (4[degrees]6'N, 11[degrees]32'E) are located in the northern part; for the Typic Kandiudult, Evindissi and Awae (3[degrees]35'N, 11[degrees]37'E) are located on the central part; and for the Typic Kandiudox, Mengomo and Nloubessa (2[degrees]35'N, 11[degrees]2'E) are located in the southern part of the studied area.
Three variable charge subsoils, a Hyper-Rhodic Ferralsol (102[degrees]43'E, 25[degrees]3'N), a Rhodic Ferralsol (110[degrees]10'E, 20[degrees]20'N), and a Haplic Acrisol (116[degrees]17'E, 28[degrees]23'N) were collected, respectively, from Kunming, Yunnan Province, Xuwen, Guangdong Province, and Jinxian, Jiangxi Province, China.
Thus, it is classified as Haplic Ferralsol (Dystric, Clayic, Rhodic) (IUSS Working Group WRB 2006) or very fine, sesquic, isohyperthermic, Rhodic Hapludox (Soil Survey Staff 2003).
Classification, parent materials, localisation in the Sao Paulo State, and sampling depth of soils Soil Classification Parent material 1 Typic Hapludox Sandstone 2 Rhodic Acrudox Argillites 3 Typic Hapludox Schist 4 Rhodic Acrustox Basalt 5 Rhodic Acrudox Diabase 6 Rhodic Acrudox Argillites 7 Typic Hapludox Basalt 8 Typic Hapludox Argillites 9 Xanthic Acrustox Basalt 10 Typic Hapludox Granite 11 Rhodic Acrustox Basalt 12 Xanthic Acrustox Diabase Soil Localisation Depth (m) 1 Aguai 0.
Freixo AA, Machado PLOA, Santos HP, Silva CA, Fadigas FS (2002) Soil organic carbon and fractions of a Rhodic Ferralsol under the influence of tillage and crop rotation systems in southern Brazil.
Freixo AA, Machado PL, Santos HP (2002) Soil organic carbon and fractions of a Rhodic Ferralsol under the influence of tillage and crop rotation systems in southern Brazil.
Thus, the classification of these soils is Rhodic Kandiustox and Typic Kandiustox for the soils under a tropical savanna climate and Rhodic Kandiudox and Typic Kandiudox for the soils under a tropical monsoonal climate.
The soil type is a Red Kandosol (Isbell 1996), Rhodic Paleustalfs (USDA Soil Survey 1975) or Profondic Lixisol (FAO 1998), with a clay content of 12% and soil pH 6.