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Aqua regia (Latin, lit. "royal water" or "king's water") is a mixture of nitric acid and hydrochloric acid,〔 The relative concentrations of the two acids in water differ, 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,〕 optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange fuming liquid. Aqua regia was so named because it can dissolve the noble metals gold and platinum. However, titanium, iridium, ruthenium, rhenium, tantalum, niobium, hafnium, osmium and rhodium are capable of withstanding its corrosive properties.〔''Encyclopædia Britannica Online''. "(Aqua regia )".〕 ==Applications== Aqua regia is primarily used to produce chloroauric acid, the electrolyte in the Wohlwill process. This process is used for refining the 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.〔Hoffman, R., (How to make an NMR sample ), Hebrew University, 10 March 2005. Accessed 31 October 2006.〕 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.〔American Industrial Hygiene Association, (Laboratory Safety Incidents: Explosions ). Accessed 8 September 2010.〕 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.〔(【引用サイトリンク】 Aqua Regia )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Aqua regia」の詳細全文を読む スポンサード リンク
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