We were reminded this earlier in February that many people aren't aware of the damage bleach and chlorine can cause to gold. Both cause a chemical reaction that disintegrates the alloys in the jewelry over time.
The most useful and important vehicle for dissolving gold is aqua regia, (royal water), composed of two parts of hydrochloric (muriatic) acid, and one part of nitric (aquafortis).
Gold can be dissolved in a sustainable manner with common household chemicals: iodine solution in ethanol, resembling diluted iodine tincture, green oxidant hydrogen peroxide and 2-mercaptobenzimidazole, a compound used in medicinal applications.
WHY BLEACH & CHLORINE DAMAGES GOLD. metals—eventually converting them into a type of salt making your gold and prongs brittle and permanently damaging the crystal structure!
Brown and Smith (1982) have found that the presence of hydrogen peroxide greatly enhances the gold and copper dissolution from gold jewellery dissolution.
As is well known, aqua regia (a mixture of three parts hydrochloric acid to one part nitric acid) can dissolve gold.
The only way gold could truly be destroyed is through nuclear reactions. However, there does exist a way to dissolve gold using “Aqua Regia,” which is a mix of hydrochloric and nitric acids.
Unlike other metals, pure gold is very unreactive. It doesn't tarnish or fade, and it won't respond to everyday chemicals like bleach.
Vinegar is incredibly corrosive. So, if your gold jewelry is made of a different metal or alloy, the vinegar will cause it to tarnish. Gold is a non-reactive metal, so it will not react to vinegar.
The effect upon chlorine on gold jewelry which is not pure 24K gold is to turn it black, due to a chemical reaction between the chlorine and various alloys which are mixed with gold to make it more durable.
For example, exposure to strong acids, such as hydrochloric acid, can dissolve gold and cause it to be destroyed. Similarly, exposure to strong bases, such as sodium hydroxide, can cause gold to corrode and become damaged. In addition to chemical reactions, gold can be damaged by physical forces.
Aqua regia is used to dissolve gold. Neither nitric acid or hydrochloric acid can do this alone. Nitric acid will act as the oxidizer and is used to form gold ions (Au3+).
Bleach is the chemical compound sodium hypochlorite. When combined with hydrochloric acid, the mixture produces chlorine that dissolves gold from gold ore. This was the first commercial method used for gold extraction.
Aqua regia is a fuming liquid. Freshly prepared aqua regia is colorless, but it turns yellow, orange or red within seconds from the formation of nitrosyl chloride and nitrogen dioxide. It was named by alchemists because it can dissolve the noble metals gold and platinum, though not all metals.
Gold will not be affected by acetone. It is not harmful to consume gold because it is tasteless. Acetone, in addition to being an organic solvent, is a widely recognized solvent.
What to do: Hold the magnet up to the gold. If it's real gold it will not stick to the magnet. (Fun fact: Real gold is not magnetic.) Fake gold, on the other hand, will stick to the magnet.
Because gold is a soft metal, it is easily scratched even with a light abrasive like baking soda.
You can also fill a cup or glass with white vinegar, and drop your gold in it, let it soak for 5-8 minutes, take it out and rinse with water. If the metal has changed its color even slightly, then the gold is not pure but if it keeps shining, then the gold is pure.
Set your jewelry or gold piece onto a flat surface. Use an eyedropper to apply a bit of vinegar and let it sit for about 15 minutes. Real gold won't change color, but fake gold will. You can also submerge the gold in a glass container with vinegar for 15 minutes.
Elements such as sulphur and chlorine react with the other metals in the gold jewelry, causing it to corrode and turn black, thus blackening the skin underneath.
If the gold is real, the piece of gold will get brighter as you put the flame to the gold. The gold won't actually catch on fire and burn; if your piece of gold starts to smoke or gets darker, it is pretty likely that you have a fake piece of gold.
Scratch Test
For this method, get an unglazed ceramic plate or piece of tiles and scrape a piece of gold across the surface. Real gold will leave a gold-colored marking, which other metals will just leave a black streak. Be careful to only scrape the tile enough to reveal a gold marking to avoid damaging your jewelry.
You can, of course, react gold with aggressive reagents like aqua regia, a 3:1 mix of HCl and HNO3. If properly done, the product is HAuCl4 or chloroauric acid.
Gold is strongly attacked by fluorine at dull-red heat to form gold(III) fluoride AuF 3. Powdered gold reacts with chlorine at 180 °C to form gold(III) chloride AuCl 3.
So the gold is a very less reactive metal. We know that most powerful acids like hydrochloric acid and nitric acid alone are not able to dissolve gold.