Platinum
From Plastics Wiki, free encyclopedia
Template:About Template:Infobox platinum Platinum (Template:PronEng) is a chemical element with the atomic symbol Pt and an atomic number of 78. It is in group 10 of the Periodic Table of Elements. A heavy, malleable, ductile, precious, gray-white transition metal, platinum is resistant to corrosion and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts, dentistry, and automobile emissions control devices. Platinum bullion has the ISO currency code of XPT. As of August 19, 2008, Platinum was worth $1,345.00 per troy ounce (approximately $43 per gram).<ref name=Kitco>Template:Cite web</ref>
Contents |
Characteristics
As a pure metal, platinum is silvery-white in appearance, lustrous, ductile, and malleable.<ref name="lagowski"/> It does not oxidize at any temperature, though it is corroded by halogens, cyanides, sulfur, and caustic alkalis. Platinum is insoluble in hydrochloric and nitric acid, though it does dissolve in aqua regia to form chloroplatinic acid, H2PtCl6.<ref name="CRC">Template:Cite book</ref>
Platinum's wear- and tarnish-resistance characteristics are well suited for making fine jewelry. Platinum is more precious than gold. The price of platinum changes along with its availability, but its price is normally more than twice the price of gold. 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> Platinum possesses high resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications.
Common oxidation states of platinum include +2, and +4. The +1 and +3 oxidation states are less common, and are often stabilized by metal bonding in bimetallic (or polymetallic) species.
Applications
The most common use of platinum is as catalyst in chemical reactions. It has been employed in this application since the early 1800s, when platinum powder was used to catalyze the ignition of hydrogen. The most important application of platinum is in automobiles as a catalytic converter, which converts harmful emissions from the engine into less harmful gases. Platinum is also used in the petroleum cracking process, which breaks down crude oil molecules into smaller organic molecules, such as gasoline. PtO2, also known as Adams' catalyst, is used as a hydrogenation catalyst, specifically for liquid vegetable oils.<ref name="krebs"/> Platinum metal also strongly catalyzes the decomposition of hydrogen peroxide into water and oxygen gas.<ref>Template:Cite book</ref>
Platinum is used as an alloying agent for various metal products, including fine wires, noncorrosive laboratory containers, medical instruments, jewelry, dental equipment, electrical contacts, and thermocouples. Platinum-cobalt, an alloy comprised of roughly 3 parts platinum and 1 part cobalt, is used to make extremely strong permanent magnets.<ref name="krebs"/> Platinum-based anodes are used in ships, pipelines, and steel piers.<ref name="CRC"/>
Chloroplatinic acid (H2PtCl6), the result of platinum dissolving in aqua regia, has various applications. It is used in photography, zinc etchings, indelible ink, plating, mirrors, porcelain coloring, and as a catalyst.<ref name="krebs">Template:Cite book</ref>
Certain platinum-containing compounds are capable of crosslinking DNA and kill cells by similar pathways to alkylating chemotherapeutic agents. Cisplatin, carboplatin and oxaliplatin are licensed examples of this class of drugs.<ref>{{#if:Richards
|{{#if:
|[[{{{authorlink}}}|{{#if:
Richards
|Richards{{#if:
A.D.
|, A.D.
}}
|{{{author}}}
}}]]
|{{#if:Richards
|Richards{{#if:
A.D.
|, A.D.
}}
|{{{author}}}
}}
}}
}}{{#if:Richards
|{{#if:Rodger, A.
| ; Rodger, A.
}}{{#if:
| ({{{date}}})
|{{#if:2007
|{{#if:
| ({{{month}}} 2007)
| (2007)
}}
}}
}}
}}{{#if:Richards
| .
}}{{#if:Richards2007
|
}}{{#ifeq:
| no
|
| {{#if: |“|"}}
}}{{#if:http://www.rsc.org/publishing/journals/CS/article.asp?doi=b609495c
|{{#ifeq:Synthetic metallomolecules as agents for the control of DNA structure||Citation is missing a title.
Either specify one, or click here and a bot will try to complete the citation details for you. }}[{{#if:http://www.rsc.org/publishing/journals/CS/article.asp?doi=b609495c|http://www.rsc.org/publishing/journals/CS/article.asp?doi=b609495c|http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&artid={{{pmc}}}}} Synthetic metallomolecules as agents for the control of DNA structure]
|Synthetic metallomolecules as agents for the control of DNA structure
}}{{#ifeq:
| no
|
| {{#if:|”|"}}
}}{{#if:
| (in {{{language}}})
}}{{#if:
| ({{{format}}})
}}{{#if:Richards
|
| {{#if:
| ({{{date}}})
|{{#if:2007
|{{#if:
| ({{{month}}} 2007)
| (2007)
}}
}}
}}
}}{{#if:Chem. Soc. Rev.
|. Chem. Soc. Rev.
}}{{#if:36
| 36
}}{{#if:
| ({{{issue}}})
}}{{#if:471–483
|: 471–483
}}{{#if:
|. {{#if:
|{{{location}}}:
}}{{{publisher}}}
}}{{#if:10.1039/b609495c
|. doi:{{#if: | {{#tag:nowiki|10.1039/b609495c}} (inactive [[]]) {{#ifeq: | | [[Category:Pages with DOIs broken since {{#time: Y | }}]] }} | }}
}}{{#if:
|. ISSN {{{issn}}}
}}{{#if:
|. PMID {{{pmid}}}
}}{{#if:
| {{#if:http://www.rsc.org/publishing/journals/CS/article.asp?doi=b609495c |. PMC:{{{pmc}}}}}
}}{{#if:
|. Bibcode: {{{bibcode}}}
}}{{#if:
|. OCLC {{{oclc}}}
}}{{#if:
|. {{{id}}}
}}{{#if:
|. Retrieved on [[{{{accessdate}}}]]{{#if: | , [[{{{accessyear}}}]] }}
}}{{#if:
| Retrieved on {{{accessmonthday}}}, {{{accessyear}}}
}}{{#if:
| Retrieved on {{{accessdaymonth}}} {{{accessyear}}}
}}{{#if:
|. [{{{laysummary}}} Lay summary]{{#if: | – {{{laysource}}}}}
}}{{#if:
| ([[{{{laydate}}}]])
}}.{{#if:
| “{{{quote}}}”
}}</ref>
In watchmaking, Vacheron Constantin, Patek Philippe, Rolex, Breitling and other companies use platinum for producing their limited edition watch series. Watchmakers highly appreciate the unique properties of platinum as it neither tarnishes nor wears out.<ref>Template:Cite web</ref>Of the 239 tonnes of platinum sold in 2006, 130 tonnes were used for automobile emissions control devices, 49 tonnes were used for jewelry, 13.3 tonnes were used in electronics, and 11.2 tonnes were used by the chemical industry as a catalyst. The remaining 35.5 tonnes produced were used in various other minor applications, such as electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.<ref name="USGS-Y-06">Template:Cite web</ref>
History
Naturally occurring platinum and platinum-rich alloys have been known for a long time. Though the metal was used by pre-Columbian Native Americans, the first European reference to platinum appears in 1557 in the writings of the Italian humanist Julius Caesar Scaliger (1484–1558) as a description of a mysterious metal found in Central American mines between Darién (Panama) and Mexico ("up until now impossible to melt by any of the Spanish arts"). The word platinum comes from the Spanish word platina, meaning "little silver."
Platinum was discussed by astronomer Antonio de Ulloa and Don Jorge Juan y Santacilia (1713–1773), both appointed by King Philip V to join a geographical expedition in Peru that lasted from 1735 to 1745. Amongst other things, Ulloa observed the platina del pinto, the unworkable metal found with gold in New Granada (Colombia). British privateers intercepted Ulloa's ship on the return voyage. Though he was well-treated in England, and even made a member of the Royal Society he was prevented from publishing a reference to the unknown metal until 1748. Before that could happen Charles Wood independently isolated the element in 1741. Major finds were discovered in Russia in 1819, which produced around 90% of the global Platinum production at the turn of the 20th century.<ref name=SmithJewelry>Template:Cite book, pages 39–40 </ref>
Due to its rarity, greater difficulty to work with and the need to alloy it with (at the time) an even more expensive metal iridium, platinum was only used in a limited way in jewelry at the end of the 19th century. This changed at beginning of the 20th century when most diamond ring mountings and most exclusive jewelry were almost completely made of platinum.<ref name=SmithJewelry/> From 1875 to 1960 the SI unit of length (the standard metre) was defined as the distance between two lines on a standard bar of an alloy of ninety percent platinum and ten percent iridium, measured at 0 degrees Celsius.
In 2007 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).
Occurrence
Platinum is an extremely rare metal, occurring as only 0.003 ppb in the Earth's crust, and is 30 times rarer than gold. It is sometimes mistaken for silver (Ag) but platinum is much whiter in appearence.
In 2005, South Africa was the top producer of platinum with an almost 80% share followed by Russia and Canada.<ref name="Platinum-Geological_Survey">Template:Cite web</ref>
Platinum is often found chemically uncombined as native platinum and alloyed with iridium as platiniridium. The platinum arsenide, sperrylite (PtAs2), is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. The rare sulfide mineral cooperite, (Pt,Pd,Ni)S, contains platinum along with palladium and nickel. Cooperite occurs in the Merensky Reef within the Bushveld complex, Gauteng, South Africa.
Platinum, often accompanied by small amounts of other platinum family metals, occurs in alluvial placer deposits in the Witwatersrand of South Africa, the Ural Mountains, and in the Absaroka Range in the American state of Montana.<ref name=NewYorkTimes>Template:Cite web</ref>
Platinum is produced commercially as a by-product of nickel ore processing in the Sudbury deposit. The huge quantities of nickel ore processed makes up for the fact that platinum is present as only 0.5 ppm in the ore.
Platinum exists in relatively higher abundances on the Moon and in meteorites. Correspondingly, platinum is found in slightly higher abundances at sites of bolide impact on the Earth that are associated with resulting post-impact volcanism, and can be mined economically; the Sudbury Basin is one such example.
Compounds
Platinum's most common oxidation states are +2 and +4. Platinum(II) chloride, PtCl2, is a green-brown powder which is insoluble in water, alcohol, and ether, though it is soluble in hydrochloric acid, HCl. Platinum(IV) oxide, PtO2, also known as Adams' Catalyst, is a black powder which is soluble in KOH solutions and concentrated acids.<ref name="perry">Template:Cite book</ref> PtO2 and the less common PtO both decompose upon heating.<ref name="lagowski">Template:Cite book</ref> Platinum(II,IV) oxide, Pt3O4, is formed in the following reaction:
- 2Pt2+ + Pt4+ + 4O2- → Pt3O4
Platinum also forms an oxide in the +6 oxidation state, PtO3.<ref name="heiserman"/>
Production
Pure platinum is isolated from its ores 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 water bath. Platinum is also non-magnetic, while nickel and iron are both magnetic. 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, while other substances are readily attacked by them. Metal impurities can be removed by stirring the mixture in either acid and recovering the remaining platinum.<ref name="heiserman">Template:Cite book</ref>
Precautions
According to the Centers for Disease Control and Prevention, 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 0.002 milligram per cubic meter of air averaged over an 8-hour work shift.<ref>Template:Cite web</ref>
Certain platinum complexes are used in chemotherapy and show good anti-tumor activity for some tumours. Cisplatin is particularly effective against testicular cancer; cure rate was improved from 10% to 85%.<ref>{{#if:Einhorn LH.
|{{#if:
|[[{{{authorlink}}}|{{#if:
|{{{last}}}{{#if:
|, {{{first}}}
}}
|Einhorn LH.
}}]]
|{{#if:
|{{{last}}}{{#if:
|, {{{first}}}
}}
|Einhorn LH.
}}
}}
}}{{#if:Einhorn LH.
|{{#if:
| ; {{{coauthors}}}
}}{{#if:
| ({{{date}}})
|{{#if:1990
|{{#if:
| ({{{month}}} 1990)
| (1990)
}}
}}
}}
}}{{#if:Einhorn LH.
| .
}}{{#if:Einhorn LH.1990
|
}}{{#ifeq:
| no
|
| {{#if: |“|"}}
}}{{#if:http://jco.ascopubs.org/cgi/content/abstract/8/11/1777
|{{#ifeq:Treatment of testicular cancer: a new and improved model||Citation is missing a title.
Either specify one, or click here and a bot will try to complete the citation details for you. }}[{{#if:http://jco.ascopubs.org/cgi/content/abstract/8/11/1777|http://jco.ascopubs.org/cgi/content/abstract/8/11/1777|http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&artid={{{pmc}}}}} Treatment of testicular cancer: a new and improved model]
|Treatment of testicular cancer: a new and improved model
}}{{#ifeq:
| no
|
| {{#if:|”|"}}
}}{{#if:
| (in {{{language}}})
}}{{#if:
| ({{{format}}})
}}{{#if:Einhorn LH.
|
| {{#if:
| ({{{date}}})
|{{#if:1990
|{{#if:
| ({{{month}}} 1990)
| (1990)
}}
}}
}}
}}{{#if:J. Clin. Oncol.
|. J. Clin. Oncol.
}}{{#if:8
| 8
}}{{#if:11
| (11)
}}{{#if:1777–81
|: 1777–81
}}{{#if:
|. {{#if:
|{{{location}}}:
}}{{{publisher}}}
}}{{#if:
|. doi:{{#if: | {{#tag:nowiki|{{{doi}}}}} (inactive [[]]) {{#ifeq: | | [[Category:Pages with DOIs broken since {{#time: Y | }}]] }} | }}
}}{{#if:
|. ISSN {{{issn}}}
}}{{#if:1700077
|. PMID 1700077
}}{{#if:
| {{#if:http://jco.ascopubs.org/cgi/content/abstract/8/11/1777 |. PMC:{{{pmc}}}}}
}}{{#if:
|. Bibcode: {{{bibcode}}}
}}{{#if:
|. OCLC {{{oclc}}}
}}{{#if:
|. {{{id}}}
}}{{#if:
|. Retrieved on [[{{{accessdate}}}]]{{#if: | , [[{{{accessyear}}}]] }}
}}{{#if:
| Retrieved on {{{accessmonthday}}}, {{{accessyear}}}
}}{{#if:
| Retrieved on {{{accessdaymonth}}} {{{accessyear}}}
}}{{#if:
|. [{{{laysummary}}} Lay summary]{{#if: | – {{{laysource}}}}}
}}{{#if:
| ([[{{{laydate}}}]])
}}.{{#if:
| “{{{quote}}}”
}}</ref> However, the side effects are severe. Cisplatin causes cumulative, irreversible kidney damage and deafness.<ref>{{#if:Von Hoff DD, et al
|{{#if:
|[[{{{authorlink}}}|{{#if:
|{{{last}}}{{#if:
|, {{{first}}}
}}
|Von Hoff DD, et al
}}]]
|{{#if:
|{{{last}}}{{#if:
|, {{{first}}}
}}
|Von Hoff DD, et al
}}
}}
}}{{#if:Von Hoff DD, et al
|{{#if:
| ; {{{coauthors}}}
}}{{#if:
| ({{{date}}})
|{{#if:1979
|{{#if:
| ({{{month}}} 1979)
| (1979)
}}
}}
}}
}}{{#if:Von Hoff DD, et al
| .
}}{{#if:Von Hoff DD, et al1979
|
}}{{#ifeq:
| no
|
| {{#if: |“|"}}
}}{{#if:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=387223&dopt=Citation
|{{#ifeq:Toxic effects of cis-dichlorodiammineplatinum(II) in man||Citation is missing a title.
Either specify one, or click here and a bot will try to complete the citation details for you. }}[{{#if:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=387223&dopt=Citation|http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=387223&dopt=Citation|http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&artid={{{pmc}}}}} Toxic effects of cis-dichlorodiammineplatinum(II) in man]
|Toxic effects of cis-dichlorodiammineplatinum(II) in man
}}{{#ifeq:
| no
|
| {{#if:|”|"}}
}}{{#if:
| (in {{{language}}})
}}{{#if:
| ({{{format}}})
}}{{#if:Von Hoff DD, et al
|
| {{#if:
| ({{{date}}})
|{{#if:1979
|{{#if:
| ({{{month}}} 1979)
| (1979)
}}
}}
}}
}}{{#if:Cancer Treat. Rep.
|. Cancer Treat. Rep.
}}{{#if:63
| 63
}}{{#if:9–10
| (9–10)
}}{{#if:1527–31
|: 1527–31
}}{{#if:
|. {{#if:
|{{{location}}}:
}}{{{publisher}}}
}}{{#if:
|. doi:{{#if: | {{#tag:nowiki|{{{doi}}}}} (inactive [[]]) {{#ifeq: | | [[Category:Pages with DOIs broken since {{#time: Y | }}]] }} | }}
}}{{#if:
|. ISSN {{{issn}}}
}}{{#if:
|. PMID {{{pmid}}}
}}{{#if:
| {{#if:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=387223&dopt=Citation |. PMC:{{{pmc}}}}}
}}{{#if:
|. Bibcode: {{{bibcode}}}
}}{{#if:
|. OCLC {{{oclc}}}
}}{{#if:
|. {{{id}}}
}}{{#if:
|. Retrieved on [[{{{accessdate}}}]]{{#if: | , [[{{{accessyear}}}]] }}
}}{{#if:
| Retrieved on {{{accessmonthday}}}, {{{accessyear}}}
}}{{#if:
| Retrieved on {{{accessdaymonth}}} {{{accessyear}}}
}}{{#if:
|. [{{{laysummary}}} Lay summary]{{#if: | – {{{laysource}}}}}
}}{{#if:
| ([[{{{laydate}}}]])
}}.{{#if:
| “{{{quote}}}”
}}</ref>. As with other ototoxic agents, deafness may be secondary to interactions with melanin in the stria vascularis.
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), the possibility that platinum free radicals could enter the body and cause adverse effects has merited study. The FDA and other countries have reviewed the issue and found no evidence to suggest toxicity in vivo.<ref>Template:Cite web</ref>
Symbol of prestige
Platinum's rarity as a metal has caused advertisers to associate it with exclusivity and wealth. "Platinum" debit cards have greater privileges than do "gold" ones. "Platinum awards" are the second highest possible, ranking above gold, silver and bronze, but below "Diamond". For example, in the United States a musical album that has sold more than 1,000,000 copies, will be credited as "platinum", whereas an album that sold more than 10,000,000 copies will be certified as “diamond”. And 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.
See also
Notes
References
- Los Alamos National Laboratory — Platinum
- Nuclides and Isotopes Fourteenth Edition: Chart of the Nuclides, General Electric Company, 1989.
- Jefferson Lab — The Element Platinum
External links
Template:Commons Template:Wiktionary
- The Platinum Group Metals Database
- A balanced historical account of the sequence of discoveries of platinum; illustrated.
- WebElements.com — Platinum
- Platinum Metals Review E-Journal
- Platinum Guild International
- United States Geological Survey Platinum-Group Metals Statistics and Information
- picture of a 999.5 fine platinum ingot in the element collection from Heinrich Pniok
Template:Jewellery Materials Template:Compact periodic tablear:بلاتين bn:প্লাটিনাম be:Плаціна bs:Platina bg:Платина ca:Platí cv:Платина cs:Platina co:Platinu cy:Platinwm da:Platin de:Platin et:Plaatina el:Λευκόχρυσος es:Platino eo:Plateno eu:Platino fa:پلاتین fr:Platine fur:Platin gv:Platinum gl:Platino ko:백금 hy:Պլատին hr:Platina io:Platino id:Platina ia:Platino is:Platína it:Platino he:פלטינה kn:ಪ್ಲಾಟಿನಮ್ ka:პლატინა sw:Platini ht:Platin ku:Platîn la:Platinum lv:Platīns lb:Platin lt:Platina jbo:jinmrplati hu:Platina mk:Платина ml:പ്ലാറ്റിനം ms:Platinum myv:Ашо сырне nl:Platina ja:白金 no:Platina nn:Platina oc:Platin nds:Platin pl:Platyna pt:Platina ro:Platină qu:Qullqiyasq:Platini scn:Plàtinu simple:Platinum sk:Platina sl:Platina sr:Платина sh:Platina fi:Platina sv:Platina ta:பிளாட்டினம் th:แพลทินัม vi:Bạch kim tg:Платина tr:Platin uk:Платина zh-yue:白金 zh:铂
