This statement cannot be understood by anyone.
I started learning about potassium, calcium, sodium, magnesium, aluminum… copper, mercury, silver, and platinum in junior high school.
Among common metals, gold is very stable and cannot be oxidized even when burned at high temperatures! The gold that can be seen in nature is basically pure gold. How can there be such a thing as gold oxide?
Because gold and silver are extremely stable, they always exist as single substances in nature, and their quantity is very rare, so they were used as the earliest currency. Apart from human factors, almost all elements are the product of supernova explosions. After iron, the abundance of substances is basically lower as time goes by. Gold is after silver, so gold is more scarce and precious.
The order in which humans smelted metals was actually the opposite of the above order. The earliest ones were copper, followed by iron, and by the time of Napoleon, aluminum was something only the richest people could own.
Having said so much, what exactly is gold oxide?
"Yeah, what is it?" Sun Jie asked. It's not like he hasn't studied chemistry before, but who studies this?
"That's it." Bai Song began to search through the sand. "The brown-black powder in here is mostly soil, but one percent of it is actually gold oxide, gold trioxide, which is the most stable oxide of gold."
"Then how can Wang Feng oxidize gold?" Captain Qin was still a little puzzled. He had never heard that gold had this property.
If you are a chemical professional, for example, someone who uses gold oxide to make paint, you must know this, but everyone on the scene is very unfamiliar with this thing. Because although gold oxide can be used to make paint, the cost...
This is a kind of paint that costs hundreds of dollars per gram and is not even shiny. There are very few places where it can be used!
"This requires a series of chemical reactions." Bai Song began to narrate:
"First of all, in addition to hydrofluoric acid, Wang Feng also bought nitric acid and hydrochloric acid. The mixture of concentrated nitric acid and concentrated hydrochloric acid is called aqua regia. Aqua regia is an extremely corrosive substance. Although it cannot be compared with fluoroantimonic acid, its oxidizing property has reached a very scary level. Aqua regia can corrode gold, but it cannot corrode plastics like polytetrafluoroethylene.
When aqua regia reacts with gold, it produces tetrachlorometallic acid, which is a light yellow, hygroscopic needle-shaped crystal.
When heated, it turns into gold chloride and gold(II) chloride.
These two chlorides react with caustic soda, also known as sodium hydroxide, to produce gold hydroxide.
Gold hydroxide is then heated to prepare gold oxide.
The reaction process here, except for the first step of aqua regia preparation and reaction which requires a certain level of technical content, the rest is simply heating and then preventing poisoning during the heating period.
Gold oxide is a brown or brown-black powder. If we put it into the soil and mix it a little more, we will never find gold unless we understand its properties.
"There is such a thing?" Everyone was amazed. Isn't this too complicated? Although Bai Song said it seemed very simple, who could remember it...
"How do I test whether what you said is correct?" Qin Wushuang was not directly misled by Bai Song's words. He had experienced all kinds of bizarre cases, but at this moment, the first thing was to confirm whether what Bai Song said was true or just conjecture, because he had to report to his leader, and he would not just look at this inference.
"There are three ways to purify gold oxide. One is to react with hydrochloric acid to turn it back into gold chloride, which then becomes a solution. Then, more active metal powders such as iron powder can be used in the solution for replacement reaction. The second method is simpler. Gold oxide is easily decomposed when exposed to light. If we put it in the sun, we will find changes. The third method is to heat it. This thing can be completely decomposed into gold and oxygen when heated to 250 degrees Celsius."
"Okay, first grab a handful of soil and put it in the sun to see if gold powder can be generated." Captain Qin nodded.
It was almost noon and the weather was good today. Everyone followed what Captain Qin said and used a large piece of evidence paper, put some soil in it, spread it out and put it in the sun.
Currency is not necessarily gold and silver, but gold and silver seem to be born as currency.
As time went by, everything happened as Bai Song had expected. Gradually, golden light appeared in the soil!
Gold!
There is a reason why Grandet loves gold!
This kind of thing can indeed arouse people's most instinctive preferences!
The total weight of the soil is only about 100 kilograms, and the more than 1,300 grams of gold is not noticeable after being mixed in with gold oxide, but once it becomes gold powder, the feeling is really wonderful.
What we call a gold mine is one where we can find a few grams of gold in one ton of gold. These are all real rich mines!
At this time, the value of this pile of soil suddenly increased countless times with this discovery.
In fact, the sealing here is very simple, just a few seals. If there really is a thief who knows this, he would have come in and stolen it long ago, but in fact no one has ever thought about this, and Wang Feng naturally would not tell anyone about this.
The bright orange light stimulated everyone's adrenaline at this moment, and Team Qin was also a little excited.
Anyway, today was his first time here, so even if it wasn't his credit, he still had some credit, what a lucky general! Captain Qin took a photo immediately and then called Director Ma.
Although he was very excited, he could not forget the rule of reporting step by step. As for reporting to Director Yin, he had to wait until all the gold was extracted before making a comment.
What if there are only 100 grams in it?
Of course, this is basically impossible. If Wang Feng put his eggs in different baskets at this time, he would have been discovered long ago.
Let professionals do the rest of the work.
Whether it was separating the soil or heating it, it was not Bai Song's turn to do it. The case involved a very large value. The value of the gold was nearly 400,000. No one dared to take it lightly. A group of nearly 10 people escorted about 100 kilograms of soil to a special laboratory together.
In order to prevent the cleaning from being messy, I even brought a few vases with me.
The steps here are very simple. To put it bluntly, even an old rural man can do it.
If you put 100 kilograms of soil in a pot and fry it, then you can find gold and then pan for it, wouldn't that be great?
Of course, that’s not how it’s done in the lab. Instead, it’s dissolved, stirred, centrifuged, separated, etc. first, and then heated specifically… After all, even gold oxide has a much higher density than soil.
But after this thing was evenly mixed into 100 kilograms of soil, no one could feel that the soil had become heavier, otherwise it would have been discovered long ago.
As it turned out, Team Qin's worries were unnecessary. 1,326 grams of gold powder were purified!
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