Aqua Regia Dissolving Gold

Au + 3HCl + HNO3 → HAuCl4 + NO + 2H2O

Aperçu

Aqua regia (3:1 mixture of HCl and HNO₃) dissolves gold, which is inert to either acid alone. Nitric acid oxidizes gold to Au³⁺ while hydrochloric acid provides chloride ions that stabilize the gold as [AuCl₄]⁻ complex. The synergy between the two acids makes aqua regia effective against noble metals.

Participants

Rôle Substance Coefficient État
Réactif Gold Au 1 (s)
Réactif Nitric Acid HNO₃ 1 (aq)
Réactif Hydrochloric Acid HCl 3 (aq)
Produit Water H₂O 2 (l)

Exemple du quotidien

During WWII, George de Hevesy dissolved the Nobel Prize gold medals of Max von Laue and James Franck in aqua regia to hide them from the Nazis.

Importance industrielle

Aqua regia is used in gold refining, analytical chemistry for dissolving noble metals, and in recovering precious metals from electronic waste.

Propriétés

Type
Redox
Réversible
Non
Énergie
Exothermique
ΔH
-150,0 kJ/mol

Réactions associées

Iron(II) to Iron(III) Oxidation by Oxygen Bleaching with Sodium Hypochlorite Copper Reduction of Silver Ion Cerium(IV) Reduction by Iron(II) Chlorine Oxidation of Bromide Copper Oxidation by Nitric Acid Hypochlorite Oxidation of Hydrogen Peroxide Hydrogen Peroxide as Oxidizing Agent (Acidic) Zinc Reduction of Silver Ion Displacement of Hydrogen from Acid by Magnesium

Frequently Asked Questions

What is the equation for Aqua Regia Dissolving Gold?
The balanced equation is: Au + 3HCl + HNO₃ → HAuCl₄ + NO + 2H₂O.
What type of reaction is Aqua Regia Dissolving Gold?
Aqua Regia Dissolving Gold is a redox reaction.
Is Aqua Regia Dissolving Gold exothermic or endothermic?
Aqua Regia Dissolving Gold is exothermic (releases energy). The enthalpy change (ΔH) is -150.0 kJ/mol.