aqua regia

aqua regia

a yellow fuming corrosive mixture of one part nitric acid and three to four parts hydrochloric acid, used in metallurgy for dissolving metals, including gold

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

aqua regia

[¦äk·wə ′rē·jə]

(inorganic chemistry)

A fuming, highly corrosive, volatile liquid with a suffocating odor made by mixing 1 part concentrated nitric acid and 3 parts concentrated hydrochloric acid; reacts with all metals, including silver and gold.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Aqua Regia

 

a mixture of concentrated hydrochloric and nitric acids, usually one part nitric acid and three parts hydrochloric acid. Aqua regia is a yellow liquid with the odor of nitrogen oxides and chlorine. It has strong oxidizing properties owing to the liberation of chlorine in the reactions

3HCl + HNO₃ = Cl₂ + NOCl + 2H₂O

2NOCl = 2NO + Cl₂

Aqua regia dissolves all metals with the exception of silver, rhodium, and iridium. It even dissolves gold—hence the name “aqua regia,” given by alchemists who considered gold the king of metals. Aqua regia is used as a laboratory reagent in such processes as the refining of gold and platinum and the production of metal chlorides.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.