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- Rhodium (Rh) Metal Synonyms:
rhodium, Rh, rhodium powder, rhodium sponge, rhodium slug, rhodium wire, rhodium metal, CAS# 7440-16-6,
Chemical Name: Rhodium
Chemical Formula: Rh
Occurring native with other platinum group metals, rhodium is the highest in electrical and thermal conductivity. It is silvery-white and has a very reflective surface. Rhodium is very hard, durable, and highly resistant to corrosion. It is harder and has a higher melting point than both platinum and palladium, making it a useful hardening element in alloying.
99.8% to 99.95%
Powder, sponge, slug, foil, and wire
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Atomic Number
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45
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Molecular Weight (g/mol.)
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102.905
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Apparent Density (g/cm3)
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12.41
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Heat Of Fusion (kJ·mol−1)
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26.59
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Specific Heat @0°C (cal/g-°C)
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.059
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Melting Point (°C)
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1966
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Boiling Point (°C)
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3727
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Thermal Conductivity @20°C (cal/s-cm°C)
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.36
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Vickers Hardness
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120 annealed
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Atomic Radius (pm)
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134
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Pyrophoric solid, Inorganic, N.O.S.
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Young's Modulus (GPa)
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380
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Appearance
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silvery white
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Crystallography
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cubic structure, face centered
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The primary use of this element is as an alloying agent for hardening platinum and palladium. These alloys are used in furnace windings, bushings for glass fiber production, thermocouple elements, electrodes for aircraft spark plugs, and laboratory crucibles. Other uses include:
a) It is used as an electrical contact material due to its low electrical resistance, low and stable contact resistance, and its high corrosion resistance.
b) Plated rhodium, made by electroplating or evaporation, is extremely hard and is used for optical instruments.
c) This metal finds use in jewelry and for decorations. It is electroplated on white gold and platinum to give it a reflective white surface. This is known as rhodium flashing in the jewelry business.
d) It also may be used in coating sterling silver in order to strengthen the metal from tarnish, as a result from the copper compound found in sterling silver.
e) It is also a highly useful catalyst in a number of industrial processes (notably it is used in the catalytic system of automobile catalytic converters and for catalytic carbonylation of methanol to produce acetic acid by the Monsanto process). It is used to catalyse addition of hydrosilanes to a double bond, a process important in manufacture of certain silicone rubbers.
f) The complex of a rhodium ion with BINAP gives a widely used chiral catalyst for chiral synthesis, as in the synthesis of menthol.
g) It is also used as a filter in mammography systems because of the characteristic x-rays it produces.
h) It is also used in high quality pen surfaces due to its high-resistance characteristics. These pens include Graf von Faber-Castell which is rather less famous than Montblanc, but produces very limited pens.
Jars and drums
Listed. For further information please call the E.P.A. at +202.554.1404
CAS# 7440-16-6
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