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Aqua regia (Latin and Ancient Italian, lit. "royal water"), aqua regis (Latin, lit. "king's water"), or nitro-hydrochloric acid is a highly corrosive mixture of acids, a fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid,^[1] optimally in a volume ratio of 1:3. It was named so because it can dissolve the so-called royal or noble metals, gold and platinum. However, titanium, iridium, ruthenium, tantalum, osmium, rhodium and a few other metals are capable of withstanding its corrosive properties.^[2]

Applications

Aqua regia is primarily used to produce chloroauric acid, the electrolyte in the Wohlwill process. This process is used for refining highest quality (99.999%) gold.

Aqua regia is also used in etching and in specific 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 spoil spectra.^[3] While chromic acid baths are discouraged because of the high toxicity of chromium and the potential for explosions, aqua regia is itself very corrosive and has been implicated in several explosions due to mishandling.^[4]

Due to the reaction between its components resulting in its decomposition, aqua regia quickly loses its effectiveness (yet remains a strong acid), so its components are usually only mixed immediately before use.

While local regulations may vary, aqua regia may be disposed of by careful neutralization, before being poured down the sink. If there is contamination by dissolved metals, the neutralized solution should be collected for disposal.^[5]^[6]

Chemistry

Dissolving gold

Pure gold precipitate produced by the aqua regia chemical refining process

Aqua regia dissolves gold, 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 ions to produce tetrachloridoaurate(III)ion anions, also in solution. The reaction with hydrochloric acid is an equilibrium reaction which favors formation of chloroaurate anions (AuCl₄⁻). This results in a removal of gold ions from solution and allows further oxidation of gold to take place. The gold dissolves to become chloroauric acid. In addition, gold may be dissolved by the free chlorine present in aqua regia. Appropriate equations are:

Au (s) + 3 Template:Chem(aq) + 6 Template:Chem (aq) → Template:Chem (aq) + 3 Template:Chem (g) + 3 Template:Chem (l) and

Template:Chem (aq) + 4 Template:Chem (aq) → Template:Chem (aq).

The oxidation reaction can also be written with nitric oxide as the product rather than nitrogen dioxide:

Au (s) + Template:Chem (aq) + 4 Template:Chem (aq) → Template:Chem (aq) + NO (g) + 2 Template:Chem (l).

If the aqua regia solution only contains gold, solid tetrachloroauric acid may be prepared by boiling off excess aqua regia, and removing residual nitric acid by repeatedly heating with hydrochloric acid. That step reduces nitric acid (see Decomposition of aqua regia). If elemental gold is desired, it may be selectively reduced with sulfur dioxide, hydrazine, oxalic acid, etc.^[7]

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 Template:Chem (aq) + 8 H⁺ (aq) → Pt⁴⁺ (aq) + 4 NO₂ (g) + 4 H₂O (l)

3Pt (s) + 4 Template:Chem (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) → Template:Chem (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.

2Pt (s) + 2HNO₃ (aq) + 8 HCl (aq) → (NO)₂PtCl₄ (s) + H₂PtCl₄ (aq) + 4 H₂O (l)

(NO)₂PtCl₄ (s) + 2 HCl (aq)

\rightleftharpoons

H₂PtCl₄ (aq) + 2 NOCl (g)

The chloroplatinous acid can be oxidized to chloroplatinic acid by saturating the solution with chlorine while heating.

H₂PtCl₄ (aq) + Cl₂ (g) → H₂PtCl₆ (aq)

Dissolving platinum solids in aqua regia was the mode of discovery for the most dense metals, iridium and osmium, both of which are found in platinum ore and will not be dissolved by the acid, instead collecting on the base of the vessel.

As a practical matter, when platinum group metals are purified through dissolution in aqua regia, gold (commonly associated with PGMs) is precipitated by treatment with iron(II) chloride. Platinum in the filtrate, as hexachloroplatinate(VI), is converted to ammonium hexachloroplatinate by the addition of ammonium chloride. This ammonium salt is extremely insoluble, and it can be filtered off. Ignition (strong heating) converts it to platinum metal:^[8]

3 (NH₄)₂PtCl₆ → 3 Pt + 2 N₂ + 2 NH₄Cl + 16 HCl

Unprecipitated hexachloroplatinate(IV) is reduced with elemental zinc, and a similar method is suitable for small scale recovery of platinum from laboratory residues.^[9]

Reaction with tin

Aqua regia reacts with tin to form tin(IV) chloride, containing tin in its highest oxidation state:

4 HCl + 2 HNO₃ + Sn → SnCl₄ + NO₂ + NO + 3 H₂O

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.

HNO₃ (aq) + 3 HCl (aq) → NOCl (g) + 2[Cl] (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.

2 NOCl (g) → 2 NO (g) + Cl₂ (g)

Because nitric oxide reacts readily with atmospheric oxygen, the gases produced also contain nitrogen dioxide, NO₂.

2 NO (g) + O₂ (g) → 2 NO₂ (g)

History

Aqua regia first appeared in the work of medieval European alchemist Pseudo-Geber, dating from the 14th century.^[10] The third of Basil Valentine’s keys shows a dragon in the foreground and a rooster eating a fox eating a rooster in the background. The rooster symbolizes gold (from its association with sunrise and the sun’s association with gold), and the fox represents aqua regia. The repetitive dissolving, heating, and redissolving (the rooster eating the fox eating the rooster) leads to the buildup of chlorine gas in the flask. The gold then volatilizes in the form of gold chloride, whose red crystals were known as dragon’s blood. The reaction was not reported in modern chemical literature until 1890.^[11]

Antoine Lavoisier called aqua regia nitro-muriatic acid in 1789.^[12] When Germany invaded Denmark in World War II, Hungarian chemist George de Hevesy dissolved the gold Nobel Prizes of German physicists Max von Laue (1914) and James Franck (1925) in aqua regia to prevent the Nazis from confiscating them. The German government had prohibited Germans from accepting or keeping any Nobel Prize after jailed peace activist Carl von Ossietzky had received the Nobel Peace Prize in 1935. De Hevesy placed the resulting solution on a shelf in his laboratory at the Niels Bohr Institute. It was subsequently ignored by the Nazis who thought the jar—one of perhaps hundreds on the shelving—contained common chemicals. After the war, de Hevesy 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. They re-cast the medals and again presented them to Laue and Franck.^[13]^[14]

Notes

43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.

References

43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.

External links

Chemistry Comes Alive! Aqua Regia
Aqua Regia at The Periodic Table of Videos (University of Nottingham)
Demonstration of Gold Coin Dissolving in Acid (Aqua Regia)

↑ The acid concentrations in water differ, and indicative values could be 65% w/v for nitric acid and 35% w/v for hydrochloric acid — that is, the actual HNO₃:HCl mass ratio is less than 1:2,
↑ Encyclopædia Britannica Online. "Aqua regia".
↑ Hoffman, R., How to make an NMR sample, Hebrew University, 10 March 2005. Accessed 31 October 2006.
↑ American Industrial Hygiene Association, Laboratory Safety Incidents: Explosions. Accessed 8 September 2010.
↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
↑ Template:Cite web
↑ Template:Ullmann
↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
↑ Encyclopædia Britannica 1911, Alchemy
↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
↑ Elements of Chemistry, p. 116
↑ "Adventures in radioisotope research", George Hevesy
↑ Template:Cite web

[1] The acid concentrations in water differ, and indicative values could be 65% w/v for nitric acid and 35% w/v for hydrochloric acid — that is, the actual HNO₃:HCl mass ratio is less than 1:2,

[2] Encyclopædia Britannica Online. "Aqua regia".

[3] Hoffman, R., How to make an NMR sample, Hebrew University, 10 March 2005. Accessed 31 October 2006.

[4] American Industrial Hygiene Association, Laboratory Safety Incidents: Explosions. Accessed 8 September 2010.

[5] 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534

[6] Template:Cite web

[ullgold-7] Template:Ullmann

[8] One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang

[9] One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang

[10] Encyclopædia Britannica 1911, Alchemy

[11] 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534

[12] Elements of Chemistry, p. 116

[13] "Adventures in radioisotope research", George Hevesy

[14] Template:Cite web

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

[12]

[13]

[14]

@@ Line 1: / Line 1: @@
-I am 32 years old and my name is Rosalyn Seton. I life in Marcq-En-Baroeul (France).<br><br>my blog post; [http://hemorrhoidtreatmentfix.com/hemorrhoid-relief hemorrhoid relief]
+{{Chembox
+| ImageFile = Aqua regia.svg
+|  ImageSize =
+|  ImageAlt =
+|  Reference = <ref group="note">The information in the infobox is only accurate if the volume ratio of [[nitric acid]] to [[hydrochloric acid]] is 1:3.</ref>
+| IUPACName = nitric acid hydrochloride
+| OtherNames = aqua regis, nitrohydrochloric acid
+| Section1 = {{Chembox Identifiers
+|  CASNo = 8007-56-5
+|  PubChem = 62687
+|  SMILES = [N+](=O)(O)[O-].Cl}}
+| Section2 = {{Chembox Properties
+|  Formula = HNO<sub>3</sub>+3 HCl
+|  Appearance = red, yellow or gold fuming liquid
+|  Density = 1.01–1.21 g/cm<sup>3</sup>
+|  MeltingPt = −42 °C
+|  BoilingPt = 108 °C
+| VaporPressure = 21 mbar
+|  Solubility = miscible in water}}
+| Section3 = {{Chembox Hazards
+|  MainHazards =
+|  NFPA-H = 3
+|  NFPA-F = 0
+|  NFPA-R = 0
+|  NFPA-O = OX
+|  FlashPt =
+|  Autoignition = }}
+}}
+[[Image:Aqua regia in Davenport Laboratories.jpg|right|thumb|Freshly prepared aqua regia to remove metal salt deposits.]]
+[[Image:Aqua regia in NMR tubes.jpg|right|thumb|Freshly prepared aqua regia is colorless, but it turns orange within seconds. Here, fresh aqua regia has been added to these [[NMR tube]]s to remove all traces of organic material.]]
+'''Aqua regia''' (<small>Latin and Ancient Italian, lit.</small> "royal water"), '''''aqua regis''''' (<small>Latin, lit.</small> "king's water"), or '''nitro-hydrochloric acid''' is a highly corrosive mixture of [[acid]]s, a fuming yellow or red solution. The [[mixture]] is formed by freshly mixing concentrated [[nitric acid]] and [[hydrochloric acid]],<ref>The acid concentrations in water differ, and indicative values could be 65% w/v for nitric acid and 35% w/v for hydrochloric acid — that is, the actual HNO<sub>3</sub>:HCl mass ratio is less than 1:2,</ref> optimally in a volume ratio of 1:3. It was named so because it can dissolve the so-called royal or [[noble metal]]s, [[gold]] and [[platinum]]. However, [[titanium]], [[iridium]], [[ruthenium]], [[tantalum]], [[osmium]], [[rhodium]] and a few other metals are capable of withstanding its corrosive properties.<ref>''Encyclopædia Britannica Online''. "[http://www.britannica.com/EBchecked/topic/31021/aqua-regia Aqua regia]".</ref>
+==Applications==
+Aqua regia is primarily used to produce [[chloroauric acid]], the [[electrolyte]] in the [[Wohlwill process]]. This process is used for refining highest quality (99.999%) gold.
+Aqua regia is also used in [[Chemical milling|etching]] and in specific [[Analytical chemistry|analytic procedures]]. It is also used in some laboratories to clean [[laboratory glassware|glassware]] of [[organic compound]]s and metal particles. This method is preferred over the "traditional" [[chromic acid]] bath for cleaning [[NMR tube]]s, because no traces of paramagnetic [[chromium]] can remain to spoil spectra.<ref>Hoffman, R., [http://chem.ch.huji.ac.il/nmr/preparation/preparation.html How to make an NMR sample], [[Hebrew University]], 10 March 2005. Accessed 31 October 2006.</ref> While [[chromic acid]] baths are discouraged because of the high toxicity of chromium and the potential for explosions, aqua regia is itself very corrosive and has been implicated in several explosions due to mishandling.<ref>[[American Industrial Hygiene Association]], [http://www.aiha.org/insideaiha/volunteergroups/labHandScommittee/Pages/IncidentsExplosions.aspx Laboratory Safety Incidents: Explosions]. Accessed 8 September 2010.</ref>
+Due to the reaction between its components resulting in its [[#Decomposition of aqua regia|decomposition]], aqua regia quickly loses its effectiveness (yet remains a strong acid), so its components are usually only mixed immediately before use.
+While local regulations may vary, aqua regia may be disposed of by careful neutralization, before being poured down the sink. If there is contamination by dissolved metals, the neutralized solution should be collected for disposal.<ref>{{cite book | title = Prudent Practices in the Laboratory: Handling and Disposal of Chemicals | year = 1995 | publisher = National Academies Press | author = Committee on Prudent Practices for Handling, Storage, and Disposal of Chemicals in Laboratories, National Research Council | pages = 160–161 | url = http://www.nap.edu/catalog.php?record_id=4911 | format = free fulltext}}</ref><ref>{{cite web | publisher = Princeton University | title = Aqua Regia | work = Laboratory Safety Manual | url = http://web.princeton.edu/sites/ehs/labsafetymanual/cheminfo/aquaregia.htm}}</ref>
+==Chemistry==
+===Dissolving gold===
+[[File:Golddust.jpg|thumb|right|Pure gold precipitate produced by the aqua regia chemical refining process]]
+Aqua regia dissolves gold, 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 [[ion]]s (Au<sup>3+</sup>). The hydrochloric acid provides a ready supply of chloride ions (Cl<sup>−</sup>), which react with the gold ions to produce tetrachloridoaurate(III)ion [[anion]]s, also in solution. The reaction with hydrochloric acid is an equilibrium reaction which favors formation of chloroaurate anions (AuCl<sub>4</sub><sup>−</sup>). This results in a removal of gold ions from solution and allows further oxidation of gold to take place. The gold dissolves to become [[chloroauric acid]]. In addition, gold may be dissolved by the free chlorine present in aqua regia. Appropriate [[Chemical equation|equations]] are:
+:Au ''(s)'' + 3 {{chem|NO|3|−}}''(aq)'' + 6 {{chem|H||+}} ''(aq)'' → {{chem|Au||3+}} ''(aq)'' + 3 {{chem|NO|2}} ''(g)'' + 3 {{chem|H|2|O}} ''(l)'' and
+:{{chem|Au||3+}} ''(aq)'' + 4 {{chem|Cl||−}} ''(aq)'' → {{chem|AuCl|4|−}} ''(aq)''.
+The oxidation reaction can also be written with [[nitric oxide]] as the product rather than [[nitrogen dioxide]]:
+:Au ''(s)'' + {{chem|NO|3|−}} ''(aq)'' + 4 {{chem|H||+}} ''(aq)'' →  {{chem|Au||3+}} ''(aq)'' + NO ''(g)'' + 2 {{chem|H|2|O}} ''(l)''.
+If the aqua regia solution only contains gold, solid [[tetrachloroauric acid]] may be prepared by boiling off excess aqua regia, and removing residual nitric acid by repeatedly heating with hydrochloric acid. That step reduces nitric acid (see [[#Decomposition of aqua regia|Decomposition of aqua regia]]). If elemental gold is desired, it may be selectively reduced with [[sulfur dioxide]], [[hydrazine]], [[oxalic acid]], etc.<ref name = ullgold>{{Ullmann | doi = 10.1002/14356007.a12_499 | title = Gold, Gold Alloys, and Gold Compounds | first1 = Hermann | last1 = Renner | first2 = Günther | last2 = Schlamp | first3 = Dieter | last3 = Hollmann | first4 = Hans Martin | last4 = Lüschow | first5 = Peter | last5 = Tews | first6 = Josef | last6 = Rothaut | first7 = Klaus | last7 = Dermann | first8 = Alfons | last8 = Knödler | first9 = Christian | last9 = Hecht | displayauthors=8}}</ref>
+===Dissolving platinum===
+[[File:Platin loest sich in heissem Koenigswasser.JPG|thumb|left|Platinum being dissolved in aqua regia]]
+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 {{chem|NO|3|-}} ''(aq)'' + 8 H<sup>+</sup> ''(aq)'' → Pt<sup>4+</sup> ''(aq)'' + 4 NO<sub>2</sub> ''(g)'' + 4 H<sub>2</sub>O ''(l)''
+:3Pt ''(s)'' + 4 {{chem|NO|3|-}} ''(aq)'' + 16 H<sup>+</sup> ''(aq)'' → 3Pt<sup>4+</sup> ''(aq)'' + 4 NO ''(g)'' + 8 H<sub>2</sub>O ''(l)''
+The oxidized platinum ion then reacts with chloride ions resulting in the chloroplatinate ion.
+:Pt<sup>4+</sup> ''(aq)'' +  6 Cl<sup>−</sup> ''(aq)'' → {{chem|PtCl|6|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 (H<sub>2</sub>PtCl<sub>4</sub>) and nitrosoplatinic chloride ((NO)<sub>2</sub>PtCl<sub>4</sub>). 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.
+:2Pt ''(s)'' + 2HNO<sub>3</sub> ''(aq)'' + 8 HCl ''(aq)'' → (NO)<sub>2</sub>PtCl<sub>4</sub> ''(s)'' + H<sub>2</sub>PtCl<sub>4</sub> ''(aq)'' + 4 H<sub>2</sub>O ''(l)''
+:(NO)<sub>2</sub>PtCl<sub>4</sub> ''(s)'' + 2 HCl ''(aq)'' <math>\rightleftharpoons</math> H<sub>2</sub>PtCl<sub>4</sub> ''(aq)'' + 2 NOCl ''(g)''
+The chloroplatinous acid can be oxidized to [[chloroplatinic acid]] by saturating the solution with chlorine while heating.
+:H<sub>2</sub>PtCl<sub>4</sub> ''(aq)'' + Cl<sub>2</sub> ''(g)'' → H<sub>2</sub>PtCl<sub>6</sub> ''(aq)''
+Dissolving platinum solids in aqua regia was the mode of discovery for the most dense metals, [[iridium]] and [[osmium]], both of which are found in platinum ore and will not be dissolved by the acid, instead collecting on the base of the vessel.
+As a practical matter, when platinum group metals are purified through dissolution in aqua regia, gold (commonly associated with PGMs) is precipitated by treatment with [[iron(II) chloride]]. Platinum in the filtrate, as hexachloroplatinate(VI), is converted to [[ammonium hexachloroplatinate]] by the addition of [[ammonium chloride]]. This ammonium salt is extremely insoluble, and it can be filtered off. Ignition (strong heating) converts it to platinum metal:<ref>{{cite journal|first1 = L. B.|last1 = Hunt|last2 = Lever |first2= F. M.|journal = Platinum Metals Review|volume = 13|issue = 4|year = 1969|pages = 126–138|title = Platinum Metals: A Survey of Productive Resources to industrial Uses|url = http://www.platinummetalsreview.com/pdf/pmr-v13-i4-126-138.pdf}}</ref>
+:3 (NH<sub>4</sub>)<sub>2</sub>PtCl<sub>6</sub> → 3 Pt + 2 N<sub>2</sub> + 2 NH<sub>4</sub>Cl + 16 HCl
+Unprecipitated hexachloroplatinate(IV) is reduced with elemental [[zinc]], and a similar method is suitable for small scale recovery of platinum from laboratory residues.<ref>{{cite journal | journal = Inorg. Synth. | title = Recovery of Platinum from Laboratory Residues | author1 = George B. Kauffman | author2 = Larry A. Teter | doi = 10.1002/9780470132388.ch61 | series = Inorganic Syntheses | year = 1963 | last3 = Rhoda | first3 = Richard N. | isbn = 9780470132388 | volume = 7 | pages = 232}}</ref>
+===Reaction with tin===
+Aqua regia reacts with [[tin]] to form [[tin(IV) chloride]], containing tin in its highest oxidation state:
+: 4 HCl + 2 HNO<sub>3</sub> + Sn → SnCl<sub>4</sub> + NO<sub>2</sub> + NO + 3 H<sub>2</sub>O
+===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.
+:HNO<sub>3</sub> ''(aq)'' + 3 HCl ''(aq)'' → NOCl ''(g)'' + 2[Cl] ''(g)'' +  2 H<sub>2</sub>O ''(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.
+:2 NOCl ''(g)'' → 2 NO ''(g)'' + Cl<sub>2</sub> ''(g)''
+Because nitric oxide reacts readily with atmospheric [[oxygen]], the gases produced also contain [[nitrogen dioxide]], NO<sub>2</sub>.
+:2 NO ''(g)'' + O<sub>2</sub> ''(g)'' → 2 NO<sub>2</sub> ''(g)''
+==History==
+[[File:Musaeum Hermeticum 1678 p 398 III. Clavis AQ27.tif|thumb|The fox in Basil Valentine's Third Key represents aqua regia, ''Musaeum Hermeticum'', 1678]]
+Aqua regia first appeared in the work of medieval European alchemist [[Pseudo-Geber]], dating from the 14th century.<ref>[http://www.1911encyclopedia.org/Alchemy Encyclopædia Britannica 1911, ''Alchemy'']</ref> The third of [[Basil Valentine]]’s keys shows a dragon in the foreground and a rooster eating a fox eating a rooster in the background. The rooster symbolizes gold (from its association with sunrise and the sun’s association with gold), and the fox represents aqua regia. The repetitive dissolving, heating, and redissolving (the rooster eating the fox eating the rooster) leads to the buildup of chlorine gas in the flask. The gold then volatilizes in the form of gold chloride, whose red crystals were known as dragon’s blood. The reaction was not reported in modern chemical literature until 1890.<ref>{{cite book|last=Principe|first=Lawrence M.|title=The secrets of alchemy|year=2012|publisher=University of Chicago Press|location=Chicago|isbn=0226682951}}</ref>
+[[Antoine Lavoisier]] called aqua regia nitro-muriatic acid in 1789.<ref>''Elements of Chemistry'', p. 116</ref> When [[Operation Weserübung|Germany invaded Denmark]] in World War II, Hungarian chemist [[George de Hevesy]] dissolved the gold [[Nobel Prize]]s of German physicists [[Max von Laue]] (1914) and [[James Franck]] (1925) in aqua regia to prevent the Nazis from confiscating them. The German government had prohibited Germans from accepting or keeping any Nobel Prize after jailed peace activist [[Carl von Ossietzky]] had received the Nobel Peace Prize in 1935. De Hevesy placed the resulting solution on a shelf in his laboratory at the [[Niels Bohr Institute]]. It was subsequently ignored by the Nazis who thought the jar—one of perhaps hundreds on the shelving—contained common chemicals. After the war, de Hevesy 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. They re-cast the medals and again presented them to Laue and Franck.<ref>[http://www.archive.org/stream/adventuresinradi01heve#page/27/mode/1up/search/medals "Adventures in radioisotope research"], George Hevesy</ref><ref>{{Cite web| publisher = The Nobel Foundation | url = http://nobelprize.org/nobel_prizes/about/medals/ | author = Birgitta Lemmel | title = The Nobel Prize Medals and the Medal for the Prize in Economics | year = 2006}}</ref>
+== See also ==
+* ''[[Aqua fortis]]''
+* ''[[Aqua vitae]]''
+* [[Digger gold]]
+* [[Sulfuric acid]]
+==Notes==
+{{Reflist|group=note}}
+==References==
+{{Reflist|2}}
+==External links==
+* [http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/AQREGIA/PAGE1.HTM Chemistry Comes Alive! ''Aqua Regia'']
+* [http://www.periodicvideos.com/videos/mv_aqua_regia.htm Aqua Regia] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
+* [http://www.youtube.com/watch?v=XoqU1GfIOkI Demonstration of ''Gold Coin Dissolving in Acid (Aqua Regia)'']
+{{DEFAULTSORT:Aqua Regia}}
+[[Category:Gold]]
+[[Category:Alchemical substances]]
+[[Category:Oxidizing mixtures]]
+[[Category:Oxidizing acids]]
+[[Category:Mineral acids]]

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