What is the chemical reaction of gold?

Reaction with Oxygen

Gold is very resistant to reacting with oxygen, which is one reason for its nobility and resistance to corrosion. However, fine gold powder can react with oxygen at high temperatures (around 250°C) to form gold(III) oxide:

2Au + 3/2O2 → Au2O3

Reaction with Halogens

Gold can react with the halogens fluorine, chlorine, bromine, iodine and astatine to form halides like AuCl3. However, it requires harsh chemical treatment to drive these reactions:

Au + 3Cl2 → AuCl3

Reaction with Alkali Metals

Alkali metals like lithium, sodium, and potassium are strong reducing agents and can reduce gold ions back to elemental gold metal:

2AuCl3 + 6Na → 3NaCl + 2Au

Reaction with Acids

Gold resists reaction with most acids like sulfuric acid and hydrochloric acid. It can react with aqua regia, a mixture of concentrated nitric acid and hydrochloric acid, which dissolves gold to form chloroauric acid.

Reaction with Bases

Gold dissolves in alkaline solutions of sodium or potassium cyanide to form complexes like [Au(CN)2]-. This process is used in gold mining and purification.

In summary, gold is relatively inert but can react with very strong oxidizing or complexing agents. Understanding gold’s key chemical reactions is important for both extraction processes and the ability to recover gold from electronic or jewelry scrap.