In this video we make gold by reduction of chloroauric acid with sodium metabisulfite.


4 grams of sodium metabisulfite is dissolved in 10mL of water.

About 2mL of water is added to 2.6g chloroauric acid to dissolve it. Now the sodium metabisulfite is added in drop by drop.



The sodium metabisulfite is reacts with the chloroauric acid to produce elemental gold, hydrochloric acid and sodium bisulfate. That brown precipitate you're seeing is actually the gold. It doesn't look like common gold because the particles of gold produced here are so small and rough that they don't reflect light in the way smooth bulk gold does. Just like how very fine sand is dull but glass is clear and shiny.

The gold dust is filtered and washed with water and then melted down into gold nuggets.