what is aqua regia?

Answer 1

-Aqua Regia is a mixture of hydrochloric acid and nitric acid. It can dissolve gold, which single acids alone cannot do. Here we see that each of the acids separately has no effect on the gold but a mixture of the two dramatically reacts with the gold. To three samples of gold are added (1) concentrated hydrochloric acid (2) concentrated hydrochloric and concentrated nitric acids and (3) concentrated nitric acid. The gold reacts only with the concentrated acid mixture which is referred to as aqua regia (royal water
-Aqua regia (Latin for "king's 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.

-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, ruining acquired spectra. 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.

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 absorb the solution with 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.

Answer 2

Aqua Regia

Answer 3

Aqua regia is a mixture of concentrated nitric acid and concentrated hydrochloric acid in the ratio 1:3 by volume.
it is represented as HNO3: 3(HCl)
it can dissolve noble metals like gold and platinum.

Answer 4

Aqua regia is a mixture of concentrated nitric acid and hydrochloric acid. It has the capacity of dissolving gold, which no single acid can do.

Answer 5

A blend of 3parts hydrochloric and 1part nitric acids
It is called aqua regia because it dissolves gold, the king of the metals, which is not dissolved in any of the two acids alone.

Answer 6

Aqua regia is a mixture of 1 part of concentrated HNO3 and 3 parts of concentrated HCl
The equation goes as:
HNO3+3HCl---->NOCl+H2O+3[Cl]

Answer 7

HNO3 + HCl... Aqua regia actually means strong water...

Answer 8

Aqua regia (Latin for "king's 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.


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, ruining acquired 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]

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 absorb the solution with 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.

[edit] 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

Au (s) + 3 NO3- (aq) + 6 H+ (aq) → Au3+ (aq) + 3 NO2 (g) + 3 H2O (l) and
Au3+ (aq) + 4 Cl- (aq) → AuCl4- (aq).
The oxidation reaction can also be written with nitric oxide as the product rather than nitrogen dioxide:

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

[edit] 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) → PtCl62- (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.

H2PtCl4 (aq) + Cl2 (g) → H2PtCl6 (aq)

[edit] 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) + 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.

2 NOCl (g) → 2 NO (g) + Cl2 (g)