Gold – the chemical element designated by Au (from the Latin word "Aurum"). Represents itself very heavy metal (density is equal 19.32 grams/centimeter cubic) yellow color. Sometimes it is necessary to dissolve gold. How does it become?
It is required to you
- - the concentrated hydrochloric acid;
- - the concentrated nitric acid;
- - reactionary capacity (flask, or laboratory glass);
- - gold piece (scrap of jewel, gold foil).
Instruction
1. That to dissolve gold, you can use methods which are still widely used in the industry at gold mining and its restoration from alloys. But it is dangerous to carry out them as the used solutions of potassium cyanide and cyanic sodium are the strongest poisons. These methods are based on formation of soluble "cyanoaurates": [Au(CN)2]-.
2. Also you can carry out reaction of gold with fluorine, but it is necessary to carry out it accurately as reaction goes at very high temperatures (from 300 to 400 degrees), also fluorine – poisonous and extremely active agent.
3. Quite easy and safe way - dissolution of gold in the well-known "royal vodka". Mix in reactionary capacity hydrochloric and nitric acids in a weight ratio 3:1.
4. Throw a gold piece, watch the reaction course. Rather quickly (even at the room temperature, without heating) it will begin to decrease in sizes, will not be dissolved completely yet.
5. Why it occurred? Under the influence of nitric acid a part chloride ions, contained in hydrochloric acid, turned into extremely active atomic chlorine. And it reacted with gold, having formed so-called. "chloraurate ion": 2Au + 3Cl2 + 2Cl− = 2 [AuCl4] −
6. The great scientist Niels Bohr, leaving the native Denmark during Hitlerite occupation, dissolved a gold medal of the Nobel Prize laureate in "royal vodka". Having returned after war, he emitted gold a chemical way, and from it made the exact copy of a medal of solution.