A chemical agent, which must have been mentioned in one way or another in all our Chemistry classes. Along with sulphuric acid and hydrochloric acid, nitric acid is one of the most known acids in the world. It has the chemical formula HNO3.
In the modern-day world, it has several uses. Some of which we have also seen in the world of Dr Stone:
i)Preparation of fertilizers, such as ammonium nitrate.
ii)Preparation of explosives e.g nitroglycerin and TNT. The latter we saw in Dr Stone at the apex of the Stone Wars.
iii) It is used in the manufacture of chemicals such as dyes.
(iv) Metallurgy (Which is the science behind metals and how they behave under various circumstances)
v) Reprocessing of spent nuclear fuel.
Within the Stone World, it has been used primarily for undoing the effects of the petrification phenomenon. For those whose minds are active even within the stone casing, a simple dash of nitric acid is all that is needed to revive them:
Even without having to keep your minds active however, nitric acid is still very essential in reviving petrified people. It is mixed with alcohol in a certain ratio, resulting in the chemical agent Nital.
Nital can then be poured onto statues that have had their minds become dormant, effectively reviving anyone. The statue must be in one piece though, otherwise the result would be…. well, nasty.
There are quite a few methods in which nitric acid can be obtained. Both natural, and through manmade means. Naturally, nitric acid occurs in certain areas of the world. For example:
a) Bat caves
b) Saltpeter caves
However, it would probably be very diluted and contaminated coming from these caves and would need to be distilled a lot before it can be used.
Aside from this statement by Xeno, there is also a saltpeter cave in Kentucky. In 1812, the cave was used to obtain potassium nitrate, which is an essential component in making gunpowder.
c) Acid rain
A type of rain that is formed when sulfur oxides and nitrogen oxides react with the moisture in the atmosphere. The rain itself contains both sulphuric acid and nitric acid.
d) Bird guano
Just like with bats, a lot of bird poop concentrated within the same region can be harnessed and refined to create nitric acid. Bird guano contains high concentrations of nitrate and ammonium.
Artificially, nitric acid can be produced through the following processes (All of which were covered in the latest chapter, 196):
(Methods 1 and 2 produce nitric acid directly, while the 3rd must be mixed with sulfuric acid)
1.The Ostwald Process
- It gets its name from the chemist who discovered it, a German named Wilhem Ostwald. It is also the same process that Senku used on Treasure Island after acquiring platinum.
Ammonia gas is oxidized to nitric oxide and nitrogen dioxide by air or oxygen, in the presence of a platinum gauze catalyst (A rhodium gauge catalyst can be used in the absence of platinum) The nitrogen dioxide is then absorbed in water in to form nitric acid. The resulting solution can be dehydrated by distillation with sulphuric acid.
This is the method that Senku used to mass produce nitric acid, considering the miracle cave had already been destroyed at that point.
2. The Electrical Arc method/ The Birkeland-Eyde Process
- Developed by the Norwegian industrialist and scientist Kristian Birkeland, along with his business partner Sam Eyde.
As per the ‘electric’ bit in the name, it uses extremely high-energy electrical arcs to react atmospheric nitrogen in the air with oxygen, producing nitric acid with water.
3. The poop method.
This is what Suika used in the chapter, but the downside is that it takes an exceedingly long amount of time to get the nitrate salts. This method doesn’t have a name. Nitrate salt comes from a very slow chemical reaction. Then, following basic displacement reactions in chemistry, nitric acid is created with the mixture of the nitrate salt with sulfuric acid.
In the story, this reaction happens naturally in the miracle cave. Senku didn’t have access to sulfuric acid before he went to the village, so the cave had ready-made nitric acid though probably very diluted and contaminated.
The method that Suika followed does the first part which is getting the nitrate salts. It combines sodium and ammonia from guano with other substances that will allow nitrate salts to form -- calcium oxide from burned shells and potassium from straw.
1. Burn calcium carbonate shells to make calcium oxide.
2. Mix in potassium carbonate from straw ashes
3. Calcium oxide gets nitrified into CaNO3 with ammonia gas, then immediately reacts with the potassium carbonate to form KNO3 + CaCO3
4. Mix in sulfuric acid and then distill
The poop/straw/shells mixture is buried to absorb the ammonia gas that is also being formed from the decomposing guano.
There are two other related processes involved in production of nitric acid. One of them is the Haber Bosch process, which was mentioned by Xeno in America. It is often combined with the Ostwald process for maximum efficiency. The process is named after the two scientists who first developed it (Fritz Haber and Carl Bosch).
The final product here of course, is ammonia. Said ammonia is then converted into nitric acid using the Ostwald process.
There is also the lesser known cyanamide process, or the Frank-Caro process. It was the first method used worldwide to fix atmospheric nitrogen, as well as come up with fertilizers. In this method, nitrogen is combined with calcium carbide at temperatures of 1000 degrees Celsius. The same calcium carbide which Senku used to down Stanley’s plane while in America.
Miscellaneous
Aside from nitric acid, there have also been other acids mentioned in Dr Stone before. Each of them important regarding the story.
From recent memory, we have:
a) Sulphuric acid- Probably the most important chemical in the story, as far as Senku’s plan to restore humanity goes. It has had so many applications so far, from making sulfanomides, to cosmetics. They have only one source for this acid, the lake near the hot springs around Ishigami Village.
b) Oxalic acid -Compared to sulphuric acid and nitric acid, this is an organic acid. It occurs naturally in rhubarb, spinach, beet leaves, Swiss chard, chocolate, cabbage, and a few other organic compounds.
Commercially, it has several uses. It can be used as bleach, metal polish, stain remover and in the manufacture of ink.
c) Hydrocholoric acid- A naturally occurring chemical in our bodies, that aids in the process of digesting proteins. Commercially, it is used to produce steel.
d)Chrolosulfuric acid
This acid is used in the manufacturing of antibacterial agents (As Senku did in preparing the sulfamonides). It is also used in production of sweetening agents such as saccharin, foam plastics along with detergents and dyes.
Big thanks to Macerator for helping explain some of this information and providing resources!
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