Knowra Rhodium Rhodium Rhodium is a rare, silvery-white transition metal with atomic number 45. Its corrosion resistance and catalytic activity make it valuable in catalytic converters and surface coatings.
Three-way catalytic converter : An exhaust-treatment device that converts nitrogen oxides, carbon monoxide, and hydrocarbons into less harmful gases. Rhodium catalyzes the reduction of nitrogen oxides in gasoline-vehicle exhaust.
Catalysis : The acceleration of a chemical reaction by a substance that is regenerated rather than consumed overall. Rhodium surfaces and complexes speed reactions by providing alternative pathways.
William Hyde Wollaston : An English chemist and physician who discovered palladium and rhodium in the early nineteenth century. Wollaston isolated rhodium from residues left after dissolving crude platinum.
Palladium : A platinum-group transition metal with atomic number 46, widely used in catalysts and electronics. Palladium also serves in vehicle catalysts, but its supply and catalytic role differ from rhodium’s.
Rhodium plating : A thin rhodium coating applied to surfaces for brightness, hardness, and tarnish resistance. Jewelry and optical components use rhodium’s reflective, corrosion-resistant surface.
Transition metal : An element whose atom or common ions have an incomplete d subshell. Rhodium’s d-electron chemistry underlies its variable bonding and catalytic activity.
Platinum ore : Natural mineral deposits containing platinum and associated metals, including palladium and rhodium. Rhodium is commonly recovered as a by-product of processing platinum ores.
Platinum : A dense, corrosion-resistant platinum-group metal with atomic number 78. Platinum is more abundant and often complements rhodium in exhaust-catalyst formulations.
Nitric acid production : An industrial process that oxidizes ammonia to produce nitric oxide, a precursor to nitric acid. Rhodium-platinum gauze catalyzes the ammonia oxidation step in the Ostwald process.
Coordination complex : A structure in which a central metal atom or ion binds surrounding molecules or ions called ligands. Molecular rhodium catalysts change reactivity as ligands bind and exchange.
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