Explain how the knowledge of chemical reactions can distinguish between real gold and fools gold?

Answer 1

Real gold is inert. No acid will touch it but one.(which is a combo-acid). Real gold is malleable more so than any other metal, so you could use the physical properties to tell whether it is real gold or not. Fools gold will crumble rather than be beaten out into fine sheets. That's why you see old miner's bite the ore, if it crumbles, it ain't real.
But what is used most often is the seperation by weight. Panning for gold. Fools gold will wash away with lighter gravels before the gold will.
Platinum is the only other thing that will remain in the pan if it is present.
Gold will melt easily. Fools gold not so.

Answer 2

There are a few methods which I can think of when it comes to differentiating those two. The first is like the previous poster said, striking it with a mallet. Pure gold is extremely malleable and thus forms sheets when struck, whereas pyrite shatters which sparks. Another test would be cyanide test - basically sodium cyanide, NaCN, is mixed with a basic/alkali solution(this is extremely important, if you mix it with acid, you will create HCN which can kill anyone instantly), and agitated for a short period of time. If it is real gold, it would be "leached" easily into the cyanide solution. In the case of pyrite however, the leaching process will not happen, as pyrite is a mineral of the formula FeS2, and thus it is impermeable to cyanide. The reason why cyanide leaches gold is because in nature, gold is a chemically inert compound, and thus forms a stable compound on its own, but in the presence of cyanide, gold forms a stable aurocyanide complex of the formula AuCN. Another experiment you could carry out is the Mohs hardness test, which involves you using a hard mineral such as say, fluorite, and scratching both pyrite and gold. As fluorite has a Mohs hardness rating of 4, it will easily scratch pure gold (Mohs hardness of 2.5) while not being able to scratch pyrite (Mohs hardness rating of 6.5). The Mohs hardness scale is purely relative, and the way it works is that minerals higher up on the scale has the ability to scratch minerals lower down on the scale, but not the other way around. It shares a similar concept to when your finger nail scratches soap, but soap does not scratch your finger nail. The simplest method would be to exploit the fact that both pyrite and gold has different densities. Gold relatively has a much higher density when compared with pyrite, so when you use a solution that has a higher density than pyrite, it will float pyrite, but gold would sink. You could even use a gold pan to Illustrate the difference in densities. Since gold is so dense, it will easily get stuck to the ridges, while pyrite is washed away. By using a centrifugal concentrator, the gold particles adhere to the walls, while pyrite floats into the overflow stream.

Answer 3

Try dropping some hydrogen peroxide 50% onto the specimen. If you get a reaction such as fizzing and bubbling then its pyrite. If there is no reaction then its gold. The oxidization of pyrite with H2O2 will produce sulphuric acid as well as a Fe2+. The Fe+ will then oxidize again to form Fe3+ plus and extra electron (e+) which is expressed as heat (exothermic reaction).
FeS2 + H2O2 = FeOOH + H2SO4 +e-
You can do the atom balance.
Pyrite + hydrogen peroxide = Iron hydroxide + Sulphuric Acid + heat
Oxidizing sulfides is a major cause of Acid Mine Drainage (AMD)
In the real world the hydrogen peroxide (H2O2) is replaced by water (H20). The precess is the same but just takes a little longer.

Answer 4

Fools gold is pyrite, which is FeS2. It reacts with water in the presence of oxygen to form sulfuric acid. Gold doesn't do that.

Answer 5

Always when I submit a question, even if it is the easiest one, they cannot give me a proper informed answer here. What happened to people that actually take the time to write an answer..