Nitric Acid 67% Lab Grade

Nitric Acid 67% (42° Baumé) (HNO3) is a highly corrosive mineral acid widely used in various industrial application.  It is a clear to pale yellow in color and is a strong oxidizing agent known for its corrosive properties.  It is commonly used in chemical manufacturing, metal processing, and as a laboratory reagent. 

Nitric Acid plays a key role in refining gold, particularly in methods like aqua regia refining and in parting processes.   Urban mining and pcb board gold recovery commonly uses nitric acid to dissolve gold.  *Ships in Level 4 Fluorinated Polyethylene Bottles, 55g ships in HDPE blue drum. 

Aqua Regia Gold Refining Process (Most Common Use)
Aqua regia is a mixture of nitric acid (HNO₃) and hydrochloric acid (HCl) in a 1:3 ratio. This combination dissolves gold, which neither acid can do alone.

Step-by-step Overview:
Preparation of Aqua Regia:

Mix 1 part nitric acid with 3 parts hydrochloric acid.

Dissolution:

Add impure gold to the aqua regia.

Nitric acid oxidizes the gold to gold ions (Au³⁺).

Hydrochloric acid provides chloride ions (Cl⁻) to form chloroauric acid (HAuCl₄), which is soluble.

Filtration:

Filter the solution to remove impurities and undissolved metals.

Precipitation:

Add a reducing agent like sodium metabisulfite (Na₂S₂O₅) to the solution.

This causes pure gold to precipitate out of solution as fine particles.

Washing & Melting:

Wash the gold powder, dry it, and melt it to form pure gold bars or granules.