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Template:About Template:Distinguish Template:Pp-move Template:Use dmy dates Template:Good article Template:Infobox platinum
Platinum is a chemical element; it has symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish Template:Lang, a diminutive of Template:Lang "silver".<ref>Template:Cite web</ref><ref>Template:OEtymD</ref>
Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarer elements in Earth's crust, with an average abundance of approximately 5 μg/kg, making platinum about 30 times rarer than gold.<ref>Template:Cite web</ref> It occurs in some nickel and copper ores along with some native deposits, with 90% of current production from deposits across Russia's Ural Mountains, Colombia, the Sudbury basin of Canada, and a large reserve in South Africa.<ref>Template:Cite book</ref>Template:Rp Because of its scarcity in Earth's crust, only a few hundred tonnes are produced annually, and given its important uses, it is highly valuable as well as a major precious metal commodity.<ref>Template:Cite news</ref>
Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts. It was referenced in European writings as early as the 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists.
Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Platinum is used in the glass industry<ref>Template:Cite journal</ref> to manipulate molten glass, which does not "wet" platinum. Elemental platinum has not been linked to adverse health effects. Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy against certain types of cancer.<ref>Template:Cite journal</ref>
Characteristics
[edit]Physical
[edit]Pure platinum is a lustrous, ductile, and malleable, silver-white metal.<ref name="lagowski">Template:Cite book</ref> Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold.<ref>Template:Cite book</ref><ref>Template:Cite book</ref>
Its physical characteristics and chemical stability make it useful for industrial applications.<ref>Template:Cite book</ref> Its resistance to wear and tarnish is well suited to use in fine jewellery.
Chemical
[edit]
Platinum has excellent resistance to corrosion. Bulk platinum does not oxidize in air at any temperature, but it forms a thin surface film of [[Platinum dioxide|Template:Chem2]] that can be easily removed by heating to about 400 °C.<ref>Template:Cite web</ref><ref name="Brewer 1953">Template:Cite journal</ref>
The most common oxidation states of platinum are +2 and +4. The +1 and +3 oxidation states are less common, and are often stabilized by metal bonding in bimetallic (or polymetallic) species. Tetracoordinate platinum(II) compounds tend to adopt 16-electron square planar geometries. Although elemental platinum is generally unreactive, it is attacked by chlorine, bromine, iodine, and sulfur. It reacts vigorously with fluorine at Template:Convert to form platinum tetrafluoride.<ref name="Lockyer1891">Template:Cite book</ref> Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia (a mixture of nitric and hydrochloric acids), to form aqueous chloroplatinic acid, Template:Chem2:<ref name="Kauuf" /><ref name="CRC">Template:Cite book</ref>
As a soft acid, the Template:Chem2 ion has a great affinity for sulfide and sulfur ligands. Numerous DMSO complexes have been reported and care is taken in the choosing of reaction solvents.<ref name="han">Template:Cite journal</ref>
In 2007, the German scientist Gerhard Ertl won the Nobel Prize in Chemistry for determining the detailed molecular mechanisms of the catalytic oxidation of carbon monoxide over platinum (catalytic converter).<ref>Template:Cite journal</ref>
Isotopes
[edit]Template:Main Platinum has six naturally occurring isotopes: Template:Chem, Template:Chem, Template:Chem, Template:Chem, Template:Chem, and Template:Chem. The most abundant of these is Template:Chem, comprising 33.83% of all platinum. It is the only stable isotope with a non-zero spin. The spin of 1/2 and other favourable magnetic properties of the nucleus are utilised in [[Platinum-195 nuclear magnetic resonance|Template:Chem NMR]]. Due to its spin and large abundance, Template:Chem satellite peaks are also often observed in Template:Chem and Template:Chem NMR spectroscopy (e.g., for Pt-phosphine and Pt-alkyl complexes). Template:Chem is the least abundant at only 0.01%. Of the naturally occurring isotopes, only Template:Chem is unstable, though it decays with a half-life of 6.5Template:E years, causing an activity of 15 Bq/kg of natural platinum. Other isotopes can undergo alpha decay, but their decay has never been observed, therefore they are considered stable.<ref name="bellidecay">Template:Cite journal</ref> Platinum also has 38 synthetic isotopes ranging in atomic mass from 165 to 208, making the total number of known isotopes 44. The least stable of these are Template:Chem and Template:Chem, with half-lives of 260 μs, whereas the most stable is Template:Chem with a half-life of 50 years. Most platinum isotopes decay by some combination of beta decay and alpha decay. Template:Chem, Template:Chem, and Template:Chem decay primarily by electron capture. Template:Chem and Template:Chem are predicted to have energetically favorable double beta decay paths.<ref name="nubase">Template:NUBASE2020</ref>
Occurrence
[edit]
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Platinum is an extremely rare metal,<ref>Template:Cite journal</ref> occurring at a concentration of only 0.005 ppm in Earth's crust.<ref>Template:Cite book</ref><ref>Template:Cite book</ref> Sometimes mistaken for silver, platinum is often found chemically uncombined as native platinum and as alloy with the other platinum-group metals and iron mostly. Most often the native platinum is found in secondary deposits in alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum-group metals. Another large alluvial deposit is in the Ural Mountains, Russia, and it is still mined.<ref name="CRC" />
In nickel and copper deposits, platinum-group metals occur as sulfides (e.g., Template:Chem2, tellurides (e.g., Template:Chem2), antimonides (PdSb), and arsenides (e.g. Template:Chem2), and as end alloys with nickel or copper. Platinum arsenide, sperrylite (Template:Chem2), is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. At Platinum, Alaska, about Template:Convert was mined between 1927 and 1975. The mine ceased operations in 1990.<ref>Template:Cite web</ref> The rare sulfide mineral cooperite, Template:Chem2, contains platinum along with palladium and nickel. Cooperite occurs in the Merensky Reef within the Bushveld complex, Gauteng, South Africa.<ref>Template:Cite journal</ref>
In 1865, chromites were identified in the Bushveld region of South Africa, followed by the discovery of platinum in 1906.<ref>Dan Oancea Platinum In South Africa Template:Webarchive. MINING.com. September 2008</ref> In 1924, the geologist Hans Merensky discovered a large supply of platinum in the Bushveld Igneous Complex in South Africa. The specific layer he found, named the Merensky Reef, contains around 75% of the world's known platinum.<ref>Template:Cite journal</ref><ref name="kirk-pt" /> The large copper–nickel deposits near Norilsk in Russia, and the Sudbury Basin, Canada, are the two other large deposits. In the Sudbury Basin, the huge quantities of nickel ore processed make up for the fact platinum is present as only 0.5 ppm in the ore. Smaller reserves can be found in the United States,<ref name="kirk-pt">Template:Cite book</ref> for example in the Absaroka Range in Montana.<ref name="NewYorkTimes">Template:Cite news</ref> In 2010, South Africa was the top producer of platinum, with an almost 77% share, followed by Russia at 13%; world production in 2010 was Template:Convert.<ref name="usgs2012-summary">Template:Cite web</ref>
New approaches to finding platinum deposits by studing ground water found some evidence of new deposits in the state of Tamil Nadu, India.<ref>Template:Cite journal</ref>
Platinum exists in higher abundances on the Moon and in meteorites. Correspondingly, platinum is found in slightly higher abundances at sites of bolide impact on Earth that are associated with resulting post-impact volcanism, and can be mined economically; the Sudbury Basin is one such example.<ref>Template:Cite book</ref>
Compounds
[edit]Halides
[edit]Hexachloroplatinic acid mentioned above is probably the most important platinum compound, as it serves as the precursor for many other platinum compounds. By itself, it has various applications in photography, zinc etchings, indelible ink, plating, mirrors, porcelain coloring, and as a catalyst.<ref name="krebs">Template:Cite book</ref>
Treatment of hexachloroplatinic acid with an ammonium salt, such as ammonium chloride, gives ammonium hexachloroplatinate,<ref name="Kauuf">Template:Cite book</ref> which is relatively insoluble in ammonium solutions. Heating this ammonium salt in the presence of hydrogen reduces it to elemental platinum. Potassium hexachloroplatinate is similarly insoluble, and hexachloroplatinic acid has been used in the determination of potassium ions by gravimetry.<ref>Template:Cite journal</ref>
When hexachloroplatinic acid is heated, it decomposes through platinum(IV) chloride and platinum(II) chloride to elemental platinum, although the reactions do not occur stepwise:<ref>Template:Cite journal</ref>
All three reactions are reversible. Platinum(II) and platinum(IV) bromides are known as well. Platinum hexafluoride is a strong oxidizer capable of oxidizing oxygen.
Oxides
[edit]Platinum(IV) oxide, Template:Chem2, also known as "Adams' catalyst", is a black powder that is soluble in potassium hydroxide (KOH) solutions and concentrated acids.<ref name="perry">Template:Cite book</ref> Template:Chem2 and the less common Template:Chem2 both decompose upon heating.<ref name="lagowski" /> Platinum(II,IV) oxide, Template:Chem2, is formed in the following reaction:
Other compounds
[edit]Unlike palladium acetate, platinum(II) acetate is not commercially available. Where a base is desired, the halides have been used in conjunction with sodium acetate.<ref name = han/> The use of platinum(II) acetylacetonate has also been reported.<ref>Template:Cite journal</ref>
Several barium platinides have been synthesized in which platinum exhibits negative oxidation states ranging from −1 to −2. These include BaPt, Template:Chem, and Template:Chem.<ref>Template:Cite journal</ref> Caesium platinide, Template:Chem, a dark-red transparent crystalline compound<ref>Template:Cite journal</ref> has been shown to contain PtTemplate:Su anions.<ref name="Jansen">Template:Cite journal</ref> Platinum also exhibits negative oxidation states at surfaces reduced electrochemically.<ref>Template:Cite journal</ref> The negative oxidation states exhibited by platinum are unusual for metallic elements, and they are attributed to the relativistic stabilization of the 6s orbitals.<ref name="Jansen" />
It is predicted that even the cation Template:Chem in which platinum exists in the +10 oxidation state may be achievable.<ref>Template:Cite web
Template:Cite journal</ref>
Zeise's salt, containing an ethylene ligand, was one of the first organometallic compounds discovered. Template:Chem name is a commercially available olefin complex, which contains easily displaceable cod ligands ("cod" being an abbreviation of 1,5-cyclooctadiene). The cod complex and the halides are convenient starting points to platinum chemistry.<ref name="han" />
Cisplatin, or Template:Chem name is the first of a series of square planar platinum(II)-containing chemotherapy drugs.<ref>Template:Cite book</ref> Others include carboplatin and oxaliplatin. These compounds are capable of crosslinking DNA, and kill cells by similar pathways to alkylating chemotherapeutic agents.<ref name="Richards">Template:Cite journal</ref> (Side effects of cisplatin include nausea and vomiting, hair loss, tinnitus, hearing loss, and nephrotoxicity.)<ref name="M.D.R.Ph.2014">Template:Cite book</ref><ref name="TaguchiNazneen2005">Template:Cite book</ref>
Organoplatinum compounds such as the above antitumour agents, as well as soluble inorganic platinum complexes, are routinely characterised using [[Platinum-195 nuclear magnetic resonance|Template:Chem nuclear magnetic resonance spectroscopy]].
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The hexachloroplatinate ion
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The anion of Zeise's salt
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Cisplatin
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History
[edit]Early uses
[edit]Archaeologists have discovered traces of platinum in the gold used in ancient Egyptian burials. For example, a small box from burial of Shepenupet II was found to be decorated with gold-platinum hieroglyphics.<ref>Template:Cite journal</ref> However, the extent of early Egyptians' knowledge of the metal is unclear. It is quite possible they did not recognize there was platinum in their gold.<ref>Template:Cite book</ref><ref>Template:Cite journal</ref>
The metal was used by Native Americans near modern-day Esmeraldas, Ecuador to produce artifacts of a white gold-platinum alloy. Archeologists usually associate the tradition of platinum-working in South America with the La Tolita Culture (Template:Circa BCE – 200 CE), but precise dates and location are difficult, as most platinum artifacts from the area were bought secondhand through the antiquities trade rather than obtained by direct archeological excavation.<ref>Template:Cite journal</ref> To work the metal, they would combine gold and platinum powders by sintering. The resulting gold–platinum alloy would then be soft enough to shape with tools.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> The platinum used in such objects was not the pure element, but rather a naturally occurring mixture of the platinum group metals, with small amounts of palladium, rhodium, and iridium.<ref name="history">Template:Cite book</ref>
European discovery
[edit]The first European reference to platinum appears in 1557 in the writings of the Italian humanist Julius Caesar Scaliger as a description of an unknown noble metal found between Darién and Mexico, "which no fire nor any Spanish artifice has yet been able to liquefy".<ref name="weeks">Template:Cite book</ref> From their first encounters with platinum, the Spanish generally saw the metal as a kind of impurity in gold, and it was treated as such. It was often simply thrown away, and there was an official decree forbidding the adulteration of gold with platinum impurities.<ref name="history" />
In 1735, Antonio de Ulloa and Jorge Juan y Santacilia saw Native Americans mining platinum while the Spaniards were travelling through Colombia and Peru for eight years. Ulloa and Juan found mines with the whitish metal nuggets and took them home to Spain. Antonio de Ulloa returned to Spain and established the first mineralogy lab in Spain and was the first to systematically study platinum, which was in 1748. His historical account of the expedition included a description of platinum as being neither separable nor calcinable. Ulloa also anticipated the discovery of platinum mines. After publishing the report in 1748, Ulloa did not continue to investigate the new metal. In 1758, he was sent to superintend mercury mining operations in Huancavelica.<ref name="weeks" />
In 1741, Charles Wood,<ref>Template:Cite book</ref> a British metallurgist, found various samples of Colombian platinum in Jamaica, which he sent to William Brownrigg for further investigation.
In 1750, after studying the platinum sent to him by Wood, Brownrigg presented a detailed account of the metal to the Royal Society, stating that he had seen no mention of it in any previous accounts of known minerals.<ref>Template:Cite journal</ref> Brownrigg also made note of platinum's extremely high melting point and refractoriness toward borax.Template:Clarify Other chemists across Europe soon began studying platinum, including Andreas Sigismund Marggraf,<ref>Template:Cite book</ref> Torbern Bergman, Jöns Jakob Berzelius, William Lewis, and Pierre Macquer. In 1752, Henrik Scheffer published a detailed scientific description of the metal, which he referred to as "white gold", including an account of how he succeeded in fusing platinum ore with the aid of arsenic. Scheffer described platinum as being less pliable than gold, but with similar resistance to corrosion.<ref name="weeks" />
Means of malleability
[edit]Karl von Sickingen researched platinum extensively in 1772. He succeeded in making malleable platinum by alloying it with gold, dissolving the alloy in hot aqua regia, precipitating the platinum with ammonium chloride, igniting the ammonium chloroplatinate, and hammering the resulting finely divided platinum to make it cohere. Franz Karl Achard made the first platinum crucible in 1784. He worked with the platinum by fusing it with arsenic, then later volatilizing the arsenic.<ref name="weeks" />
Because the other platinum-family members were not discovered yet (platinum was the first), Scheffer and Sickingen made the false assumption that due to its hardness—which is slightly more than for pure iron—platinum would be a relatively non-pliable material, even brittle at times, when in fact its ductility exceeds that of gold and its malleability similar to gold's. Their assumptions could not be avoided because the platinum they experimented with was highly contaminated with minute amounts of platinum-family elements such as osmium and iridium, amongst others, which embrittled the platinum alloy. Alloying this impure platinum residue called "plyoxen"Template:Citation needed with gold as the only solution at the time to obtain a pliable compound. Presently, very pure platinum is readily available, and extremely long wires can easily be drawn from pure platinum due to its crystalline structure, which is similar to that of many soft metals.<ref>Platinum Template:Webarchive. mysite.du.edu</ref>
"Platinum age" in Spain
[edit]In 1786, Charles III of Spain provided a library and laboratory to Pierre-François Chabaneau to aid in his research of platinum. Chabaneau succeeded in removing various impurities from the ore, including gold, mercury, lead, copper, and iron. This led him to believe he was working with a single metal, but in truth the ore still contained the yet-undiscovered platinum-group metals. This led to inconsistent results in his experiments. At times, the platinum seemed malleable, but when it was alloyed with iridium, it would be much more brittle. Sometimes the metal was entirely incombustible, but when alloyed with osmium, it would volatilize. After several months, Chabaneau succeeded in producing 23 kilograms of pure, malleable platinum by hammering and compressing the sponge form while white-hot. Chabeneau realized the infusibility of platinum would lend value to objects made of it and so started a business with Joaquín Cabezas producing platinum ingots and utensils. This started what is known as the "platinum age" in Spain.<ref name="weeks" />
Production
[edit]
Platinum, along with the rest of the platinum-group metals, is obtained commercially as a by-product from nickel and copper mining and processing. During electrorefining of copper, noble metals such as silver, gold and the platinum-group metals as well as selenium and tellurium settle to the bottom of the cell as "anode mud", which forms the starting point for the extraction of the platinum-group metals.<ref name="usgs2010-yearbook">Template:Cite web</ref>
If pure platinum is found in placer deposits or other ores, it is isolated from them by various methods of subtracting impurities. Because platinum is significantly denser than many of its impurities, the lighter impurities can be removed by simply floating them away in a liquid. Platinum is paramagnetic, whereas nickel and iron are both ferromagnetic. These two impurities are thus removed by running an electromagnet over the mixture. Because platinum has a higher melting point than most other substances, many impurities can be burned or melted away without melting the platinum. Finally, platinum is resistant to hydrochloric and sulfuric acids, whereas other substances are readily attacked by them. Metal impurities can be removed by stirring the mixture in either of the two acids and recovering the remaining platinum.<ref name="heiserman">Template:Cite book</ref>
One suitable method for purification for the raw platinum, which contains platinum, gold, and the other platinum-group metals, is to process it with aqua regia, in which palladium, gold and platinum are dissolved, whereas osmium, iridium, ruthenium and rhodium stay unreacted. The gold is precipitated by the addition of iron(II) chloride and after filtering off the gold, the platinum is precipitated as ammonium chloroplatinate by the addition of ammonium chloride. Ammonium chloroplatinate can be converted to platinum by heating.<ref>Template:Cite journal</ref> Unprecipitated hexachloroplatinate(IV) may be reduced with elemental zinc, and a similar method is suitable for small scale recovery of platinum from laboratory residues.<ref>Template:Cite book</ref> Mining and refining platinum has environmental impacts.<ref>Template:Cite web</ref>
Applications
[edit]
Of the 218 tonnes of platinum sold in 2014, 98 tonnes were used for vehicle emissions control devices (45%), 74.7 tonnes for jewelry (34%), 20.0 tonnes for chemical production and petroleum refining (9.2%), and 5.85 tonnes for electrical applications such as hard disk drives (2.7%). The remaining 28.9 tonnes went to various other minor applications, such as medicine and biomedicine, glassmaking equipment, investment, electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.<ref name="usgs2014-yearbook">Template:Cite web</ref>
Catalyst
[edit]The most common use of platinum is as a catalyst in chemical reactions, often as platinum black. It has been employed as a catalyst since the early 19th century, when platinum powder was used to catalyze the ignition of hydrogen. In an automobile catalytic converter, it completes the combustion of low concentrations of unburned hydrocarbons from the exhaust into carbon dioxide and water vapor. Platinum is also used in the petroleum industry as a catalyst in a number of separate processes, but especially in catalytic reforming of straight-run naphthas into higher-octane gasoline that becomes rich in aromatic compounds. Template:Chem2, also known as Adams' catalyst, is used as a hydrogenation catalyst, specifically for vegetable oils.<ref name="krebs" /> Platinum also strongly catalyzes the decomposition of hydrogen peroxide into water and oxygen<ref>Template:Cite book</ref> and it is used in fuel cells<ref>Template:Cite book</ref> as a catalyst for the reduction of oxygen.<ref>Template:Cite journal</ref>
Green energy transition
[edit]As a fuel cell catalyst, platinum enables hydrogen and oxygen reactions to take place at an optimum rate. It is used in platinum-based proton exchange membrane (PEM) technologies required in green hydrogen production as well as fuel cell electric vehicle adoption (FCEV).<ref>Template:Citation</ref><ref>Template:Cite journal</ref>
Standard
[edit]
From 1889 to 1960, the meter was defined as the length of a platinum-iridium (90:10) alloy bar, known as the international prototype meter. The previous bar was made of platinum in 1799. Until May 2019, the kilogram was defined as the mass of the international prototype of the kilogram, a cylinder of the same platinum-iridium alloy made in 1879.<ref name="meter">Template:Cite book</ref>
The Standard Platinum Resistance Thermometer (SPRT) is one of the four types of thermometers used to define the International Temperature Scale of 1990 (ITS-90), the international calibration standard for temperature measurements. The resistance wire in the thermometer is made of pure platinum (NIST manufactured the wires from platinum bar stock with a chemical purity of 99.999% by weight).<ref name="bipm">Template:Cite web</ref><ref name="nist">Template:Cite web</ref> In addition to laboratory uses, Platinum Resistance Thermometry (PRT) also has many industrial applications, industrial standards include ASTM E1137 and IEC 60751.
The standard hydrogen electrode also uses a platinized platinum electrode due to its corrosion resistance, and other attributes.<ref name="HollemanAF">Template:Cite journal</ref>
As an investment
[edit]Platinum is a precious metal commodity; its bullion has the ISO currency code of XPT. Coins, bars, and ingots are traded or collected. Platinum finds use in jewellery, usually as a 90–95% alloy, due to its inertness. It is used for this purpose for its prestige and inherent bullion value.<ref>Template:Cite web</ref><ref>Template:Cite web</ref>
In watchmaking, Vacheron Constantin, Patek Philippe, Rolex, Breitling, and other companies use platinum in some of their watches. Watchmakers appreciate the unique properties of platinum, as it is more durable than gold, but similar to gold, it does not tarnish.<ref>Template:Cite web</ref>
During periods of sustained economic stability and growth, the price of platinum tends to be as much as twice the price of gold, whereas during periods of economic uncertainty,<ref name="TheSpeculativeInvestor">Template:Cite web</ref> the price of platinum tends to decrease due to reduced industrial demand, falling below the price of gold. Gold prices are more stable in slow economic times, as gold is considered a safe haven.<ref>Template:Cite journal</ref> Although gold is also used in industrial applications, especially in electronics due to its use as a conductor, its demand is not so driven by industrial uses.<ref>Template:Cite journal</ref> In the 18th century, platinum's rarity made King Louis XV of France declare it the only metal fit for a king.<ref name="mineralszone">Template:Cite web</ref>
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1,000 cubic centimeters of 99.9% pure platinum, worth about US$696,000 at 29 Jun 2016 prices<ref name="WolframAlpha">Template:Cite web</ref>
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Platinum price 1970–2022
Other uses
[edit]In the laboratory, platinum wire is used for electrodes; platinum pans and supports are used in thermogravimetric analysis because of the stringent requirements of chemical inertness upon heating to high temperatures (~1000 °C). Platinum is used as an alloying agent for various metal products, including fine wires, noncorrosive laboratory containers, medical instruments, dental prostheses, electrical contacts, and thermocouples. Platinum-cobalt, an alloy of roughly three parts platinum and one part cobalt, is used to make relatively strong permanent magnets.<ref name="krebs" /> Platinum-based anodes are used in ships, pipelines, and steel piers.<ref name="CRC" /> Platinum drugs are used to treat a wide variety of cancers, including testicular and ovarian carcinomas, melanoma, small-cell and non-small-cell lung cancer, myelomas and lymphomas.<ref name="apps">Template:Cite journal</ref>
Symbol of prestige in marketing
[edit]Platinum's rarity as a metal has caused advertisers to associate it with exclusivity and wealth. "Platinum" debit and credit cards have greater privileges than "gold" cards.<ref>Template:Cite journal</ref> "Platinum awards" are frequently the highest, or near highest possible, often ranking above "gold", "silver" and "bronze". For example, in the United States, a musical album that has sold more than 1 million copies will be credited as "platinum", though an album that has sold more than 10 million copies will be certified as "diamond".<ref>Template:Cite book</ref> Some products, such as blenders and vehicles, with a silvery-white color are identified as "platinum". Platinum is considered a precious metal, although its use is not as common as the use of gold or silver. The frame of the Crown of Queen Elizabeth The Queen Mother, manufactured for her coronation as Consort of King George VI, is made of platinum. It was the first British crown to be made of this particular metal.<ref>Template:Cite book</ref>
Health risks
[edit]Elemental platinum is not believed to cause significant health risks and no adverse effects have been attributed to platinum exposure.<ref>Template:Citation</ref> The National Institute for Occupational Safety and Health has set a recommended exposure limit (REL) for platinum as 1 mg/m3 over an 8-hour workday.<ref>Template:Cite web</ref>
As platinum is a catalyst in the manufacture of the silicone rubber and gel components of several types of medical implants (breast implants, joint replacement prosthetics, artificial lumbar discs, vascular access ports, etc.), the possibility that platinum could enter the body and cause adverse effects has merited study. The Food and Drug Administration and other institutions have reviewed the issue and found no evidence to suggest toxicity in vivo.<ref>Template:Cite web</ref><ref>Template:Cite journal</ref> Chemically unbonded (metallic, colloidal, or amalgam) platinum has been identified by the FDA as a "fake cancer 'cure'".<ref name="fda">Template:Cite web</ref>
Short-term exposure to platinum salts may cause irritation of the eyes, nose, and throat, and long-term exposure may cause both respiratory and skin allergies. The current OSHA standard is 2 micrograms per cubic meter of air averaged over an 8-hour work shift.<ref>Template:Cite web</ref>
See also
[edit]- Chelated platinum
- Iron–platinum nanoparticle
- List of countries by platinum production
- Mixed metal oxide electrode
- Nox (unit)
- Platinum group
- Platinum in Africa
- Platinum nanoparticle
- Platinum print
- Skot (unit)
- 2000s commodities boom
References
[edit]Further reading
[edit]External links
[edit]Template:Commons Template:Wiktionary
- Platinum at The Periodic Table of Videos (University of Nottingham)
- NIOSH Pocket Guide to Chemical Hazards – Platinum Centers for Disease Control and Prevention
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Template:Periodic table (navbox) Template:Jewellery Template:Platinum compounds Template:Authority control