Freshly prepared aqua regia is colorless, but it turns orange within seconds. Here, fresh aqua regia has been added to these NMR tubes to remove all traces of organic material.

Aqua regia (Latin for "royal water") is a highly corrosive, fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and concentrated hydrochloric acid, usually in a volumetric ratio of one to three respectively. It is one of the few reagents that dissolves gold and platinum. It was so named because it can dissolve the so-called royal, or noble metals, although tantalum, iridium, and a few other metals are able to withstand it. Image File history File linksMetadata Download high-resolution version (1200x1600, 358 KB) en:Aqua regia used to clean en:NMR tubes File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Aqua regia NMR tube Metadata This file contains additional... Image File history File linksMetadata Download high-resolution version (1200x1600, 358 KB) en:Aqua regia used to clean en:NMR tubes File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Aqua regia NMR tube Metadata This file contains additional... An NMR tube filled with a colorless sample, sealed with a green polyethylene cap and Parafilm Left to right: Flame, septum and polyethylene cap sealed NMR tubes Aqua regia has been added to these NMR tubes to remove all traces of organic material. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... A mixture in chemistry is the product of a mechanical blending or mixing of chemical substances like elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup [1] . While there are no chemical changes in a mixture, physical... The chemical compound nitric acid (HNO3), also known as aqua fortis and spirit of nitre, is an aqueous solution of hydrogen nitrate (anhydrous nitric acid). ... The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride gas (HCl). ... A reagent or reactant is any substance used in a chemical reaction. ... GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... Noble metals are metals that are resistant to corrosion or oxidation, unlike most base metals. ... General Name, Symbol, Number tantalum, Ta, 73 Chemical series transition metals Group, Period, Block 5, 6, d Appearance gray blue Atomic mass 180. ... General Name, Symbol, Number iridium, Ir, 77 Chemical series transition metals Group, Period, Block 9, 6, d Appearance silvery white Atomic mass 192. ...

Applications

Aqua regia is used in etching and in certain analytic procedures. It is also used in some laboratories to clean glassware of organic compounds and metal particles. This method is preferred over the "traditional" chromic acid bath for cleaning NMR tubes because no traces of paramagnetic chromium can remain to ruinacquired spectra.^[1] It is important to note that chromic acid baths are discouraged because of chromium toxicity and the potential for explosions. Aqua regia is itself very corrosive and has been implicated in several explosions as well due to mishandling and it should not be used unless gentler cleaning techniques such as the use of brushes, sonication, detergents, or milder oxidisers are inadequate.^[2] This page discusses the industrial applications of the etching process. ... Analytical chemistry is the analysis of material samples to gain an understanding of their chemical composition and structure. ... Brown glass jars with some clear lab glassware in the background Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiments and other work in science, especially in chemistry and biology laboratories. ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; therefore, carbides, carbonates, carbon oxides and elementary carbon are not organic (see below for more on the definition controversy... In chemistry, chromic acid is a chromium (Cr) compound, yet to be isolated, with the formula H2CrO4. ... An NMR tube filled with a colorless sample, sealed with a green polyethylene cap and Parafilm Left to right: Flame, septum and polyethylene cap sealed NMR tubes Aqua regia has been added to these NMR tubes to remove all traces of organic material. ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6, 4, d Appearance silvery metallic Atomic mass 51. ...

Due to the reaction between its components resulting in its decomposition, aqua regia quickly loses its effectiveness. As such, its components should only be mixed immediately before use. While local regulations may vary, aqua regia may be disposed of by carefully neutralizing with an appropriate agent - such as sodium bicarbonate - before pouring down the sink. If there is a large amount of metal in solution with the acid, it may be preferable to carefully neutralize it, and adsorb the solution on a solid material such as vermiculite before discarding it with solid waste. This practice should not be used when EPA regulated or otherwise toxic metals are present. Sodium bicarbonate is the chemical compound with the formula NaHCO3. ... Vermiculite is a natural mineral which expands with the application of heat. ... A heavy metal is any of a number of higher atomic weight elements, which has the properties of a metallic substance at room temperature. ...

Chemistry

Dissolving gold

Aqua regia dissolves gold, even though neither constituent acid will do so alone, because, in combination, each acid performs a different task. Nitric acid is a powerful oxidizer, which will actually dissolve a virtually undetectable amount of gold, forming gold ions (Au³⁺). The hydrochloric acid provides a ready supply of chloride ions (Cl^-), which react with the gold to produce chloraurate anions, also in solution. The reaction with hydrochloric acid is an equilibrium reaction which favors formation of chloraurate anions (AuCl₄^-). This results in a removal of gold ions from solution and allows further oxidation of gold to take place, and so the gold is dissolved. In addition, gold may be oxidized by the free chlorine present in aqua regia. Appropriate equations are: In chemistry, a chemical equation is a symbolic representation of a chemical reaction. ...

Au (s) + 3 NO₃^- (aq) + 6 H⁺ (aq) → Au³⁺ (aq) + 3 NO₂ (g) + 3 H₂O (l)

Au³⁺ (aq) + 4 Cl^- (aq) → AuCl₄^- (aq)

The oxidation reaction can also be written with nitric oxide as the product rather than nitrogen dioxide. R-phrases , , , , S-phrases , , , Supplementary data page Structure and properties n, εr, etc. ... [1] R-phrases , S-phrases , , , , , Supplementary data page Structure and properties n, εr, etc. ...

Au (s) + NO₃^- (aq) + 4 H⁺ (aq) → Au³⁺ (aq) + NO (g) + 2 H₂O (l)

Dissolving platinum

Similar equations can be written for platinum. As with gold, the oxidation reaction can be written with either nitric oxide or nitrogen dioxide as the nitrogen oxide product.

Pt (s) + 4 NO ₃^- (aq) + 8 H⁺ (aq) → Pt⁴⁺ (aq) + 4 NO₂ (g) + 4 H₂O (l)

3Pt (s) + 4 NO ₃^- (aq) + 16 H⁺ (aq) → 3Pt⁴⁺ (aq) + 4 NO (g) + 8 H₂O (l)

The oxidized platinum ion then reacts with chloride ions resulting in the chloroplatinate ion.

Pt⁴⁺ (aq) + 6 Cl^- (aq) → PtCl₆^2- (aq)

Experimental evidence reveals that the reaction of platinum with aqua regia is considerably more complex. The initial reactions produce a mixture of chloroplatinous acid (H₂PtCl₄) and nitrosoplatinic chloride ((NO)₂PtCl₄). The nitrosoplatinic chloride is a solid product. If full dissolution of the platinum is desired, repeated extractions of the residual solids with concentrated hydrochloric acid must be performed.

Pt (s) + 2 HNO₃ (aq) + 4 HCl (aq) → (NO)₂PtCl₄ (s) + 3 H₂O (l) + 1/2 O₂ (g)

(NO)₂PtCl₄ (s) + 2 HCl (aq) → H₂PtCl₄ (aq) + NOCl (g)

The chloroplatinous acid can be oxidized to chloroplatinic acid by saturating the solution with chlorine while heating. Chloroplatinic Acid Please see dihydrogen hexachloroplatinate (IV) hexahydrate ...

H₂PtCl₄ (aq) + Cl₂ (g) → H₂PtCl₆ (aq)

Decomposition of aqua regia

Upon mixing of concentrated hydrochloric acid and concentrated nitric acid, chemical reactions occur. These reactions result in the volatile products nitrosyl chloride and chlorine as evidenced by the fuming nature and characteristic yellow color of aqua regia. As the volatile products escape from solution, the aqua regia loses its potency. Nitrosyl chloride is the chemical compound NOCl. ... General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Standard atomic weight 35. ...

HNO₃ (aq) + 3 HCl (aq) → NOCl (g) + Cl₂ (g) + 2 H₂O (l)

Nitrosyl chloride can further decompose into nitric oxide and chlorine. This dissociation is equilibrium-limited. Therefore, in addition to nitrosyl chloride and chlorine, the fumes over aqua regia contain nitric oxide. R-phrases , , , , S-phrases , , , Supplementary data page Structure and properties n, εr, etc. ...

2 NOCl (g) → 2 NO (g) + Cl₂ (g)

History

Jabir ibn Hayyan, medieval manuscript drawing, anonymous

Hydrochloric acid was first discovered around the year 800 by the Iranian alchemist Abu Musa Jabir ebn Hayyan, by mixing common salt with vitriol (sulfuric acid). Jabir's invention of gold-dissolving aqua regia, consisting of hydrochloric acid and nitric acid, contributed to the effort of alchemists to find the philosopher's stone. Download high resolution version (575x707, 204 KB)alchemist Jabir ibn Hayyan, from a 15th c. ... Download high resolution version (575x707, 204 KB)alchemist Jabir ibn Hayyan, from a 15th c. ... Events December 25, Rome, coronation of Charles the Great (Charlemagne) as emperor by Pope Leo III. Celtic monks begin work on the Book of Kells on the Island of Iona. ... Jabir ibn Hayyan Abu Musa Jabir ibn Hayyan (Arabic: جابر بن حيان) (c. ... This articles section called Other facts does not adequately cite its references or sources. ... It has been suggested that this article or section be merged into sulfuric acid. ... Sulfuric acid, H2SO4, is a strong mineral acid. ... The chemical compound nitric acid (HNO3), also known as aqua fortis and spirit of nitre, is an aqueous solution of hydrogen nitrate (anhydrous nitric acid). ... The philosophers stone, in Latin lapis philosophorum, is a legendary substance that supposedly could turn inexpensive metals such as lead into gold (chrysopoeia in the Greek language) and/or create an elixir that would make humans younger, thus delaying death. ...

When Germany invaded Denmark in World War II, the Hungarian chemist George de Hevesy dissolved the gold Nobel Prizes of Max von Laue and James Franck into aqua regia to prevent the Nazis from stealing them. He placed the resulting solution on a shelf in his laboratory at the Niels Bohr Institute. After the war, he returned to find the solution undisturbed and precipitated the gold out of the acid. The gold was returned to the Royal Swedish Academy of Sciences and the Nobel Foundation presented new medals to Laue and Franck.^[3] Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... George Charles de Hevesy (born as Hevesy György, also known as Georg Karl von Hevesy) (August 1, 1885 in Budapest – July 5, 1966) was a Hungarian chemist who was important in the development of the tracer method where radioactive tracers are used to study chemical processes, e. ... The Nobel Prizes (Swedish: ) are awards in physics, chemistry, literature, peace, physiology or medicine. ... Max von Laue (October 9, 1879 - April 24, 1960) was a German physicist, who studied under Max Planck. ... James Franck (August 26, 1882 - May 21, 1964) was a German-born physicist and Nobel laureate. ... The Niels Bohr Institute is part of the Niels Bohr Institute for Astronomy, Physics and Geophysics of the University of Copenhagen. ...

References

1. ^ Hoffman, R., How to make an NMR sample, Hebrew University, 10 Mar 2005. Accessed 31 Oct 2006.
2. ^ American Industrial Hygiene Association, Laboratory Incidents: Explosions, 8 Dec 2004. Accessed 31 Oct 2006.
3. ^ Birgitta Lemmel (2006). The Nobel Prize Medals and the Medal for the Prize in Economics. The Nobel Foundation.

The Hebrew University of Jerusalem (האוניברסיטה העברית בירושלים) is one of Israels biggest and most important institutes of higher learning and research. ... The American Industrial Hygiene Association (AIHA) is a professional membership organization of industrial hygienists, and occupational health and safety, and environmental health professionals. ...

External links

• Chemistry Comes Alive! Aqua Regia
• The Columbia Encyclopedia: Aqua Regia
• Argon Lab Systems: Aqua Regia