In the 21st century.
Compared with hand-made generators, the concept of electrolysis may be more widely spread.
Especially the electrolysis of saturated salt water, this is a chemical practical reaction that is as basic as it can be.
In an electrolysis experiment, a reduction reaction occurs at the cathode, where it gains electrons.
The anode will undergo an oxidation reaction and lose electrons.
At the same time, after the electrolysis reaction occurs, some anoxic acid salts of active metals will generate alkali at the cathode.
Oxylate salts of inactive metals will generate acids at the anode. .
In addition, after the electrolysis reaction occurs, the cathode will also produce solid and reducing gases.
As for the choice of cathode and anode...
A common operation for electrolyzing saturated brine is to use copper as the cathode and carbon rods as the anode.
Of course.
If the conditions are average, two carbon rods actually have no effect.
However, there is a special feature of electrolyzed saturated salt water, that is, chlorine gas easily reacts with sodium hydroxide.
That is, 2NaOH+Cl2=NaCl+NaClO+H2O.
Therefore, in modern industry, porous and permeable separators are generally used to separate the anode chamber and the cathode chamber, so that the two do not come into contact.
However, the current Song Dynasty obviously cannot do this kind of technology, so Xu Yun is considering...
Salt Bridge.
In the courtyard.
After preparing the generator materials, Xu Yun turned around and asked Lao Su:
"Master, where is the white crystal block I bought from the sour plum shop?"
Lao Su pointed to a package on the left and replied:
"That's the package, Xiao Wang. If I hadn't made a good judgment, this thing should be saltpeter?"
Xu Yun walked over and opened the package, examined it carefully, and affirmed:
"Yes, it is indeed saltpeter.
I heard that the old man spoke with a Hexi accent, so I guess the saltpeter was transported from Hexi. "
Old Su nodded thoughtfully and said:
"I see. No wonder he came back in the first year and told me that the couple thought he was a spy sent by his colleagues at first, and even clamored to report him to the official.
Later, he had no choice but to reveal his badge to the county government and invite a government official on the street to testify. Only then did the other party agree to sell him some crystal nuggets, and the price was not low. "
Xu Yun shook the saltpeter in his hand with great satisfaction and said:
"It's normal for saltpeter of such quality to be expensive. It can save a lot of trouble."
When Xu Yun saw iced sour plum juice in the sour plum shop, he thought about two possibilities for the old man to make ice.
One is the ice cellar.
The second is saltpeter.
Among them, the possibility of ice cellars is not very high. After all, the production cost of ice cellars in this era is not low. Only people’s courtyards will build ice cellars to store ice.
Therefore, although Xu Yun was not sure that the opponent must have saltpeter in his hand, he was almost seventy percent sure.
With saltpeter, potassium nitrate can be prepared.
Students who didn’t fail biology should remember it.
Potassium nitrate is a common salt bridge.
The so-called salt bridge refers to an electrolyte that can communicate between two beakers, allowing anions and cations to move freely from the cathode to the anode.
With the potassium nitrate salt bridge, it can prevent the chlorine gas generated by electrolysis of salt water from reacting with sodium hydroxide in the electrolytic cell to the greatest extent, thus promoting the production of chlorine gas.
As for the preparation of potassium nitrate, it is also very simple:
First dissolve the saltpeter in water and then remove the sediment.
After heating, evaporation and concentration, KNO3 crystals can be obtained after cooling.
Potassium nitrate crystals have extremely strong solubility, so these crystals are redissolved in water, and a salt bridge is created.
After all the preparatory work is completed.
Xu Yun put the refined salt prepared by Mr. Xie into the water and started stirring with a glass rod.
soon.
The solution started to become a little cloudy.
Xu Yun looked at Lao Su:
"Master, could you please bring the idiot?"
Although Lao Su didn't quite understand his intention to operate on Xu Yun, he still handed him a funnel covered with gauze.
Pattering——
Xu Yun poured the turbid liquid down.
With the gauze blocking, some insoluble impurities are filtered out.
Then he divided the filtered solution into two large cups, let's call them cup A and cup B.
Um.
It's just a cup, without the word "hood".
Then he first detached the A cup to the electrolysis equipment - the electrolysis equipment was not very different from the equipment used in later generations to electrolyze saturated salt water. The anode had a conduit that led to another water container.
At this time, the donkey had already accumulated full power for the clockwork. As soon as Xu Yun turned on the switch, the rotor quickly began to rotate.
The volume of the solution he prepared this time was about one liter. According to the Nernst equation, the theoretical voltage value for successful electrolysis can be calculated to be 13V.
Therefore, the effective number of turns of the generator he designed is 17 turns.
Of course.
Xu Yun's preset number of rotor slots is 2, and the speed is 300 revolutions per minute. The calculated accurate value is 15.7, which logically should be 16 revolutions.
However, considering the ancient copper wire and the conduction effect, he still chose to wind it an extra turn to be safer.
After all, if the electrolysis voltage does not exceed 30 volts, it will basically be fine.
After all preparations were completed, Cup A started electrolysis.
Although there are still many impurities in the solution at this time, such as magnesium chloride and sodium sulfate, the solution does not seem to be pure.
However, Xu Yun's operation mainly focused on the collection of gas. Sodium chloride accounted for the majority of the solution, so it was not affected by other cations at all.
Just mention it here.
This concept seems easy to understand, but it specifically involves the concepts of superpotential and Gibbs free energy.
Just like a piece of knowledge that everyone knows in middle school:
Electrolysis of dilute sulfuric acid is equivalent to electrolysis of water.
But in the professional...or university field, this statement is actually wrong.
Because in the high school range, the discharge order of hydroxyl radicals in water is before the oxygen-containing acid radicals, so the oxygen-containing acid radicals cannot discharge electricity.
But in fact, due to the existence of overpotential, a side reaction will occur during the period to generate H2S2O8, which exceeds the standard electrode potential of 2.01V, forming an overpotential situation.
Therefore, electrolysis of dilute sulfuric acid is actually different from electrolysis of water.
Realize and then return to where you were.
With the introduction of electric energy, the sodium chloride in cup A quickly undergoes electrolysis.
The cathode generates hydrogen gas.
The anode generates chlorine gas.
The generated gas escapes and is collected by a glass tube into a container placed in a dark place where no light can be seen.
Chlorine is at the bottom and hydrogen is at the top.
Ignite and burn, and white mist will form at the mouth of the bottle. (I don’t recommend you try it, it’s easy to explode)
The white mist was led by the glass tube to another container filled with water, where it dissolved with water.
Thus.
A higher concentration of hydrochloric acid is now prepared.
Seeing this, some students may ask:
That's not right, wouldn't it be possible to get hydrochloric acid by directly dissolving chlorine gas into water? Why bother?
the reason is simple:
Hydrochloric acid can also be obtained by dissolving the chlorine gas generated by the electrolysis reaction in water, but this reaction actually generates a mixed solution of chlorine and water.
In addition to hydrochloric acid, there are also many ions such as Cl2, H2O, HClO, H+, ClO-, Cl-, OH- and so on.
Not only is the reaction reversible, but the concentration of hydrochloric acid is also very low.
The effect is much worse than the hydrochloric acid prepared by Xu Yun.
Of course.
Again, don’t react with chlorine and hydrogen easily, otherwise an explosion may easily occur.
His gaze returned to its original position.
After the operation was completed, Xu Yun packed the hydrochloric acid.
Glancing at Lao Su next to him, he was not in a hurry to make the next move, but asked Lao Su:
"Master, can you find someone to catch a few monsters?"
"盱甴? What do you want that thing for?"
"The villain is free to use."
Lao Su saw a lot of Xu Yun's strange operations today. He didn't ask any more questions. He glanced at Mr. Xie Duguan beside him and ordered:
"In the first year of the year, you quickly find someone to catch some monsters."
Mr. Xie nodded and turned around to arrange the manpower.
Mentioned a long time ago.
Cockroaches have been on the earth for hundreds of millions of years. They have a history older than dinosaurs. They can even be said to be one of the oldest living creatures on earth.
In addition, the hygiene level in the Song Dynasty was much lower than that in later generations. It was summer again, so naturally cockroaches could be seen everywhere.
So not long after, Mr. Xie came back with a glass bottle:
"Master, Brother Wang, we've caught him."
Xu Yun took a look at the glass bottle and was immediately happy.
Good guy.
It's the American cockroach again, the same old trick.
At this time, these American cockroaches were showing their teeth and claws in the bottle. It was obvious that the food in Lao Su's family was good.
Xu Yun then leveled the glass bottle and signaled Lao Su to step aside.
Open the bottle, pick up the hydrochloric acid and pour it into it.
There is a kind of tiec protein on the surface of cockroaches. Hydrochloric acid is the most corrosive and destructive of all acids for this protein. Therefore, hydrochloric acid is actually a very effective cockroach killer.
Bang——
As the hydrochloric acid was splashed, the cockroaches panicked and crawled around in the bottle.
But soon, their body surfaces were corroded by hydrochloric acid and holes were formed.
In just a few minutes, it finally...
Dying from anger.
American cockroach.JPG.
See this situation.
Lao Su suddenly shrank his pupils and said in horror:
"This...how is this possible? Table salt is actually poisonous?"
Xu Yun smiled slightly when he saw this but said nothing.
Lao Su's reaction was what he expected, or to put it bluntly, this was actually one of his goals:
In ancient times when microscopic knowledge was almost zero, there was nothing more impactful than isolating 'poisonous' substances from the refined salt we eat every day.
When the next thing he does is completed, Lao Su will definitely ask him some questions, and they will definitely involve the microscopic field.
With such an example that happened before us as evidence, some words are obviously easier to convince.
Then Xu Yun stored the prepared hydrochloric acid and picked up another thing that Lao Xu had prepared:
Poison heavy stone.
Toxic barium is a barium-containing ore, which was often used in later industries as an acid to detoxify barium ore to produce barium chloride.
Xu Yun washed the poisonous heavy stones that had been ground into powder, picked up a small spoon, and dropped them into the hydrochloric acid solution.
Half an hour later.
A bottle of mixed solution was prepared successfully.
Xu Yun began to add sodium hydroxide to it again - this was one of the products of the previous electrolysis. Although there were other cations in it, they were the target products themselves, so they would not affect the reaction process at all.
It really took Xu Yun a lot of effort to make every link closely linked.
As everyone knows.
In the toxinite solution, the pH when Fe3+ is completely precipitated is 3.2, the pH when Mg2+ is completely precipitated is 11.1, and the pH when Ca2+ is completely precipitated is 13.9. (Paper reference 10.16283/.hgkwyjg.1996.06.014)
Therefore, Xu Yun does not need to care about the real-time data of pH value at all, he only needs to observe the precipitation changes during the reaction process.
Another hour passed.
After filtration with Tiga sodium hydroxide.
One bottle of standard barium chloride solution.
At this point, the rest is very simple, that is...
Junior high concept of coarse salt purification.
First, add excess BaCl2 to remove sulfate ions.
The reaction formula is BaCl2+Na2SO4=BaSO4↓+2NaCl.
Then add excess NaOH to remove magnesium ions:
MgCl2+2NaOH=Mg(OH)2↓+2NaCl
In the third step, soda is added, which is sodium carbonate. This stuff can be seen everywhere in the glass making industry. The purpose is to remove calcium ions and barium ions in BaCl2.
Finally, add HCl to remove excess NaOH and Na2CO3 - if this process is possible, you can use pH test paper to observe the amount of hydrochloric acid. If not, don't worry about how much you can pour. If there is more, just evaporate it.
Then another hour passed.
A large cluster of precipitated sodium chloride crystals emerged.
Xu Yun weighed the doses and dissolved them into the water.
that's all.
A cup of standard concentration saline officially arrived in 1100 AD.
And the other side.
Looking at Xu Yun who was busy tinkering with the preparation of garlic injection, Lao Su finally couldn't help it anymore:
"Xiao Wang, why can salt water be produced into such a poisonous substance after being treated in this way?"
............
Note:
I wonder if anyone will ask why it takes so much trouble to make salt. Let me tell you, this is not just for making salt....
In order to make the subsequent plot fit together, you don’t know that my friend was harassed by me... Ahem, how tired I am from writing...
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