4523. Gold Trihydroxide

Nomenclature

CAS number: 1303-52-2
Auric hydroxide.
AuH3O3; mol wt 247.99.
Au 79.43%, H 1.22%, O 19.35%.
Au(OH)3.

Description and references

Usually contains about 3H2O and hence about 65% gold. May be prepd in lab according to the equation 2KAuCl4 + 3Na2CO3 + 3H2O → 2Au(OH)3 + 6NaCl + 2KCl + 3CO2: Lydén, Z. Anorg. Allg. Chem. 240, 157 (1939).

Properties

Brown powder; dec by sunlight to metallic gold; also slowly dec with age or at 100°, and completely at 250°. Practically insol in water. Sol in soln of NaCN, in HCl or concd HNO3. With NH3 yields gold fulminate which explodes easily in dry form. Protect from light.

Use

In gold-plating solns; for decorating porcelains.