Gold chloride

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(This page is about gold(III) chloride. For information about gold(I) chloride and gold(I,III) chloride, see respective page.)

Acidic gold chloride, 250g/liter.

The gold chloride you will encounter in gold refining is gold (III) chloride (also called auric chloride). It is a beautiful red crystalline material that decomposes at low temperature to give elemental gold and chlorine gas.

Gold chloride present in acidic solutions is called acid gold chloride or chloroauric acid, and exists as a HAuCl4.

Chemical formula

Gold chloride actually have the formula Au2Cl6 when crystalline but the empirical formula AuCl3 is often used since the atoms are split in ions when in solution.

Heating gold chloride

Gold chloride is a fragile compound and is easily split by heat. Above 160 °C it starts to decompose into gold(I) chloride and chlorine gas. Above 420 °C gold(I) chloride reduces into metallic gold and gold(III) chloride. This is the basis of gas phase transport used for creating ultra pure gold and gold crystals.

   AuCl3 → AuCl + Cl2 (>160 °C)
   3 AuCl → AuCl3 + 2 Au (>420 °C)


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