7439-88-5 Usage
Uses
Used in Jewelry and Decorative Industry:
Iridium is used as an alloying metal for platinum and palladium, enhancing their resistance to chemical attack, corrosion, hardness, and tensile strength. This makes it suitable for use in jewelry and decorative purposes.
Used in Electrical Industry:
Iridium is used as an alloy metal in electrical contacts and thermocouples due to its high melting point and resistance to corrosion.
Used in Scientific and Laboratory Applications:
Iridium is used in the manufacture of crucibles and devices that require high temperatures, as well as in special laboratory vessels because it does not react with most chemical substances.
Used in Standard Weights and Measures:
An alloy of iridium and platinum is used as the standard kilogram weight due to its non-corrosive and non-oxidizing properties, ensuring that it does not change its weight over time.
Used in Radiography and Cancer Treatment:
The radioisotope iridium-192 is used in the examination of ferrous welds and other radiographic applications, as well as in high-dose radiation therapy for the treatment of prostate and other forms of cancer.
Used in Polymer LED Technology:
Iridium complexes, such as Ir(mppy)3, are used in polymer LED technology to increase efficiency through triplet harvesting.
Used in Manufacturing:
Iridium is used in the manufacturing of crucibles, hardening platinum, and making nibs for fountain pen points.
Used in Ballpoint Pens:
Iridium is used in the tips of ballpoint pens due to its durability and resistance to wear.
Used in Chemical Industry:
Iridium is used as a catalyst for the carbonylation of methanol to create acetic acid.
Used in Military Applications:
Iridium, as an alloy with platinum, was once used in bushing the vents of heavy ordnance, and in a finely powdered condition (iridium black) for painting porcelain black.
Reactions
At ordinary temperatures iridium exhibits strong resistance to chemical attack. At elevated temperatures of about 600°C, iridium metal combines with oxygen to form a coating of iridium dioxide, IrO2. Similarly, the metal reacts with halogens only at elevated temperatures. It reacts with fluorine at 250°C, forming iridium hexafluoride, IrF6, and, to a lesser extent, iridium tetrachloride IrCl4. Heating with chlorine at 600°C produces iridium trichloride, IrCl3. Iridium forms alloys with several metals—mostly platinum group metals.
Iridium does not react with concentrated acids or with molten alkalies.
Isotopes
There are 55 isotopes of iridium, two of which are stable and account for theelement’s total existence on Earth. Those two are Ir-191, which makes up 37.3% of theamount in the Earth’s crust, and Ir-193, which constitutes 62.7% of iridium’s existenceon Earth. All the other 53 isotopes of iridium are radioactive with half-lives ranging froma few microseconds to a few hours or days and up to a few hundred years. Theseunstable isotopes are all artificially produced.
Origin of Name
The name iridium comes from the Latin word iris, meaning “rainbow,”
because of the element’s highly colored salts.
Characteristics
Iridium is one of the so-called platinum group of 6 transition elements (Ru, Rh, and Pd ofperiod 5 and Os, Ir, and Pt of period 6). It is resistant to strong acids, including aqua regia.It is the only metal that can be used in equipment that must withstand temperatures up to2,300°C or 4,170°F. Iridium can be poured into casts after it becomes molten. As it cools, itbecomes crystalline and, while in this state, can be pulled into wires and formed into sheets.Unlike steel, which becomes more malleable (less brittle) after annealing (a process of heatingfollowed by slowly cooling), iridium is just the opposite—it becomes more brittle and impossibleto work into shapes after cooling.
History
Discovered in 1803 by Tennant in the residue left when crude platinum is dissolved by aqua regia. The name iridium is appropriate, for its salts are highly colored. Iridium, a metal of the platinum family, is white, similar to platinum, but with a slight yellowish cast. It is very hard and brittle, making it very hard to machine, form, or work. It is the most corrosion-resistant metal known, and was used in making the standard meterbar of Paris, which is a 90% platinum–10% iridium alloy. This meter bar was replaced in 1960 as a fundamental unit of length (see under Krypton). Iridium is not attacked by any of the acids nor by aqua regia, but is attacked by molten salts, such as NaCl and NaCN. Iridium occurs uncombined in nature with platinum and other metals of this family in alluvial deposits. It is recovered as a by-product from the nickel mining industry. The largest reserves and production of the platinum group of metals, which includes iridium, is in South Africa, followed by Russia and Canada. The U.S. has only one active mine, located at Nye, MT. The presence of iridium has recently been used in examining the Cretaceous-Tertiary (K-T) boundary. Meteorites contain small amounts of iridium. Because iridium is found widely distributed at the K-T boundary, it has been suggested that a large meteorite or asteroid collided with the Earth, killing the dinosaurs, and creating a large dust cloud and crater. Searches for such a crater point to one in the Yucatan, known as Chicxulub. Iridium has found use in making crucibles and apparatus for use at high temperatures. It is also used for electrical contacts. Its principal use is as a hardening agent for platinum. With osmium, it forms an alloy that is used for tipping pens and compass bearings. The specific gravity of iridium is only very slightly lower than that of osmium, which has been generally credited as being the heaviest known element. Calculations of the densities of iridium and osmium from the space lattices give values of 22.65 and 22.61 g/cm3, respectively. These values may be more reliable than actual physical measurements. At present, therefore, we know that either iridium or osmium is the densest known element, but the data do not yet allow selection between the two. Natural iridium contains two stable isotopes. Forty-five other isotopes, all radioactive, are now recognized. Iridium (99.9%) costs about $100/g.
Hazard
The elemental metal form of iridium is almost completely inert and does not oxidizeat room temperatures. But, as with several of the other metals in the platinum group,several of iridium’s compounds are toxic. The dust and powder should not be inhaled oringested.
Flammability and Explosibility
Nonflammable
Purification Methods
Iridium is a silver white hard solid which oxidises on the surface in air. Scrape the outer tarnished layer until silver clear and store it under paraffin. It is stable to acids but dissolves in aqua regia. [Gilchrist Chem Rev 32 277 1943.]
Check Digit Verification of cas no
The CAS Registry Mumber 7439-88-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,4,3 and 9 respectively; the second part has 2 digits, 8 and 8 respectively.
Calculate Digit Verification of CAS Registry Number 7439-88:
(6*7)+(5*4)+(4*3)+(3*9)+(2*8)+(1*8)=125
125 % 10 = 5
So 7439-88-5 is a valid CAS Registry Number.
InChI:InChI=1/Ir
