Dilute nitric or nitrous acid solution containing halide ions as effective media for pure gold dissolution

Abstract

Bromide salts are more effective than chloride salts in gaining the ability of dissolving gold in dilute aqueous nitric acid solution. At 60 °C, a piece of gold-wire (ca. 20 mg) is dissolved in 20 mL of as low as 0.10 mol L⁻¹ HNO₃ solution containing 1.0–5.0 mol L⁻¹ NaBr and the dissolution rate constant, log(k/s⁻¹), increases linearly with increasing NaBr concentration.