GOLD in KÖNIGSWASSER auflösen [𝟰𝗞] | JJChemistry

Gold is the king of metals, chemically extremely noble, valuable and vulnerable to almost any substance. There is a famous acid that can dissolve gold, royal water. To make royal water, I need two acids that are already strong in themselves. 37% smoking salt acid and 60% salpetic acid. The mixing ratio is 3 mol HCl to 1 mol HNO3. This corresponds to about 150 ml of my salt acid to 50 ml of salpetic acid. The royal water is slowly starting to form. After a little stirring and waiting for an hour, the royal water is deep orange. The orange color is created by the formation of nitrosyl chloride. Now the gilded bitcoin is ready. The gold is slowly starting to dissolve. Gold is a very noble metal, which means that it has a high electrochemical potential. The potentials of many metals are listed in so-called electrochemical voltage series. A metal can only be attacked or oxidized by another substance if this substance has an even higher potential. This is important to remember. The potential of gold is 1.5 V. There are only a few substances and compounds above that. The potential of salpetic acid is 0.96 V. This is not enough to dissolve gold, because it is less. The potential of salt acid is even lower. Salt acid acts on its proton, so the potential is at plus minus 0 V. This is also the reason why copper and silver cannot be dissolved by salt acid. With plus 0.35 V and plus 0.8 V, the potentials of the two noble metals are above that of salt acid. However, they are less than the potential of salpetic acid. Therefore, salpetic acid can dissolve copper and silver, but not gold. Interestingly, a mixture of salpetic acid and salt acid, i.e. the royal water, manages to dissolve gold. These two acids form, if you mix them together, three different products. First, the reddish-brown nitrosyl chloride, a very strong oxidation agent, water and nesting chlorine. Nesting means, literally translated, coming into the world. So it is chlorine that is now formed in this moment because of the reaction. Normally, two chlorine atoms form the chlorine molecule Cl2. This is usually visible as yellow gas. However, the fact that chlorine does not appear as a molecule, but as a single element, only happens in nesting processes like here. Nesting substances are often much more reactive than when they are already available in bottles or storage containers. And chlorine gas is already aggressive if it is not nesting. Normal chlorine gas has a potential of plus 1.36 volts and thus comes close to gold. The nesting chlorine has an even higher potential, so that even that of gold exceeds. And for this reason, it can oxidize gold and thus dissolve it. A soluble yellow gold complex is formed, namely the tetrachloro-gold. This complex is the second main reason why gold is dissolved in royal water. But I will explain this in a future video, in which I also work with gold. Since the coin is only gold-plated and mostly consists of copper and zinc, nothing can be seen of the orange coloring of the royal water, just as little as of the yellow coloring of the resulting complex. If it were a pure gold coin, I could have isolated the tetrachloro-gold acid as a powder. As a replacement for this, I have something very special here, namely hexachloroplatinic acid. The coin itself is almost 40 years old and certainly stored in a glass of powder. Here you can see the beautiful orange coloring of the rare powder-shaped platinic acid. There are metals that royal water cannot have. The closest example is silver. Silver can be dissolved in sulphate acid, but not in royal water. This cannot be justified by the potentials, because otherwise royal water would dissolve silver, but with a very specific reaction. And I actually intended to show that, because my fork is 800 absorbed, so the silver content is 80%. To my horror, however, the royal water reacted anyway with my fork, which is why I pulled it out again. I guess it's because it's not pure silver. Pure silver would protect itself with an insoluble silver chloride layer, so that the acid cannot attack the metal further. Organic substances also hardly attack royal water. This paper here is not at all interested in the fact that it is just being dipped in royal water. Sulfuric acid, on the other hand, would quickly carbonize paper and sugar. But nothing happens here. Many thanks to my channel members and all viewers, because you support my channel a lot. If you have wishes and suggestions for further videos, feel free to write them in the comments.