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Chapter 124 – The Song Dynasty Also Wanted To Kill Cockroaches

Chapter 124 The Song Dynasty also wants to kill cockroaches

In the 21st century.

Compared to the hand rubbing generator, the concept of electrolysis may be spread more widely.

Especially the electrolysis of saturated salt water, this is a basic chemical operation reaction that can no longer be basic.

In an electrolysis experiment, a reduction reaction occurs at the cathode, at which point it gains electrons.

The anode will undergo an oxidation reaction and lose electrons.

At the same time, after the electrolytic reaction occurs, some anoxic acid salts of active metals will generate alkali at the cathode.

Oxygenates of inactive metals will generate acid at the anode.

In addition, after the electrolysis reaction occurs, the cathode will also produce solids and reducing gases. . .

As for the choice of cathode and anode.

The common operation of electrolyzing saturated salt water is to use copper as the cathode and carbon rod as the anode.

Of course.

If the conditions are average, the two carbon rods will not affect the situation.

However, there is a special feature of electrolytic saturated salt water, that is, chlorine gas easily reacts with sodium hydroxide.

That is 2NaOH+Cl2=NaCl+NaClO+H2O.

So in modern industry, a porous and permeable diaphragm is generally used to separate the anode chamber and the cathode chamber so that the two will not be in contact.

But the current Da Song obviously cannot do this kind of technology, so Xu Yun is considering

Salt Bridge.

In the courtyard.

After preparing the materials for the generator, Xu Yun turned around and asked Old Su:

“Master, where is the white crystal block bought from the sour plum shop?”

Old Su pointed to a package on the left, and replied:

“That package is, Xiao Wang, if the old man’s judgment is not correct, this thing should be saltpeter?”

Xu Yun walked over and opened the package, carefully identified it, and affirmed:

“Yes, it is indeed saltpeter.

I heard that the old man spoke with a Hexi accent, so the saltpeter must have been transported from Hexi. “

Old Su nodded thoughtfully, and said:

“So that’s the case, no wonder the first year came back and told me that the couple thought he was a spy sent by their colleagues at first, and even clamored to report to the authorities.

Later, he had no choice but to show the waist badge of the county government, and invited the government servants on the street to testify, and the other party was willing to sell him some crystal blocks, and the price was not low. “

Xu Yun shook the saltpeter in his hand very satisfied, and said:

“Saltpeter of such quality is expensive, but it’s normal. It can save a lot of trouble.”

When Xu Yun saw iced plum juice in the sour plum shop, Xu Yun 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, and only large courtyards can make ice cellars to store ice cubes.

Thus, although Xu Yun wasn’t sure that the other party must have saltpeter in his hand, he was almost 70% sure.

With saltpeter, potassium nitrate can be prepared.

Students who failed in biology should remember it.

Potassium nitrate is a common salt bridge.

The so-called salt bridge refers to an electrolyte that can communicate in two beakers, so that anions and cations can 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, thereby promoting the production of chlorine gas.

As for the preparation of potassium nitrate is also very simple:

First dissolve the saltpeter with water, and then remove the sediment.

Heating, evaporation and concentration, and KNO3 crystals can be obtained after cooling.

Potassium nitrate crystals are extremely soluble, so redissolving these crystals in water creates a salt bridge.

After preparations for a lot of pre-procedural work are completed.

Xu Yun put the refined salt prepared by Mr. Xie into the water, and started stirring with a glass rod.

soon.

The solution starts to become a little cloudy.

Xu Yun looked at Lao Su:

“Sir, please bring the gauze.”

Although Old Su didn’t quite understand the intention of Xu Yun’s operation, he still handed him a funnel covered with gauze.

patter—

Xu Yun poured the turbid liquid down.

With the barrier of gauze, some insoluble impurities are filtered out.

Then he divided the filtered solution into two cups, let’s call them A cup and B cup.

Um.

It’s just a cup, without the word “hood”.

Then he first connected the A cup to the electrolysis equipment—the electrolysis equipment is not very different from the later generation equipment for electrolyzing saturated salt water, in which the anode has a conduit that leads to another water container.

At this time, the donkey had already fully charged the spring, and as soon as Xu Yun turned on the switch, the rotor quickly began to spin.

The volume of the solution he prepared this time is about one liter. According to the Nernst equation, the theoretical value of the voltage 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 preset the number of rotor slots as 2, and the speed is 300 revolutions per minute. The calculated accurate value is 15.7, which should be 16 revolutions in theory.

However, considering the ancient copper wire and the conduction effect, he chose to make an extra turn, just to be on the safe side.

After all, the voltage of electrolysis does not exceed 30 volts, which is basically nothing.

After everything was prepared, the A cup started electrolysis.

Although there are still many impurities in the solution at this time, such as magnesium chloride, sodium sulfate, etc., the solution does not seem to be pure.

But Xu Yun’s operation this time is mainly about gas collection, and sodium chloride accounts for the majority of the solution, so it will not be affected by other cations at all.

By the way, here.

This concept seems to be easy to understand, but it specifically involves the concepts of overpotential and Gibbs free energy.

It’s like a 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 category of high school, the discharge sequence of hydroxide in water is in front of oxyacid, so oxyacid cannot discharge electricity.

But in fact, because of the existence of overpotential, there will be a side reaction to generate H2S2O8, which exceeds the standard electrode potential of 2.01V, forming an overpotential situation.

Therefore, the electrolysis of dilute sulfuric acid is actually not the same as the electrolysis of water.

Realize and return to the original place.

With the introduction of electric energy, the sodium chloride in the A cup is quickly electrolyzed.

The cathode generates hydrogen gas.

The anode generates chlorine gas.

The resulting gas escapes and is collected by the glass tube into a container placed in a dark place where no light can be seen.

Chlorine is on the bottom and hydrogen is on the top.

Ignite and burn, and white mist is generated at the mouth of the bottle. (It is not recommended to try it, it is easy to explode)

The white mist is led to another container filled with water by the glass tube, and it dissolves with water.

Thus.

A higher concentration of hydrochloric acid is prepared.

Seeing this, some students may ask:

No, can’t you get hydrochloric acid by directly dissolving chlorine gas in water? Why is it so troublesome?

the reason is simple:

The chlorine gas produced by the electrolysis reaction can be dissolved in water to obtain hydrochloric acid, but this reaction actually produces a mixed solution of chlorine and water.

In addition to hydrochloric acid, there are Cl2, H2O, HClO, H+, ClO-, Cl-, OH- and many other ions.

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.

Remind again, do not easily react with chlorine and hydrogen, otherwise it is easy to cause an explosion.

The line of sight returns to the original place.

After the operation, Xu Yun divided the hydrochloric acid into packages.

Looking at Lao Su beside him, he was not in a hurry to make the next move, but asked Lao Su:

“Master, can someone catch some cockroaches?”

“A cockroach? Why do you want that thing?”

“The villain has his own uses.”

Old Su has seen a lot of Xu Yun’s strange operations today, so he didn’t ask any more when he saw what he said.

“In the first year, you quickly find someone to catch some cockroaches.”

Old Duguan Xie nodded, turned around and arranged for the staff.

Mentioned a long time ago.

Cockroaches have appeared on the earth for hundreds of millions of years, and their history is longer than that of dinosaurs. It can even be said to be one of the longest living creatures on earth.

In addition, the sanitation level in the Song Dynasty was much lower than that of later generations. It was summer again, and cockroaches were naturally everywhere.

So not long after, Mr. Xie walked back with a glass bottle:

“Master, Brother Wang, the cockroach has been caught.”

Xu Yun took a look at the glass bottle and was immediately happy.

Good guy.

It’s Periplaneta americana again, old trick.

At this time, these American cockroaches are showing their teeth and claws in the bottle. Obviously, the food in the old Su family is good.

Then Xu Yun put the glass bottle flat and signaled Lao Su to get out of the way.

Open the bottle, pick up the hydrochloric acid and pour it into it.

Normally speaking, hydrochloric acid has a strong corrosion effect on organisms, but it is very difficult to kill organisms.

However, cockroaches are very special:

There is a protein called tiec on the surface of this thing, and hydrochloric acid is the most destructive to the corrosion of this protein, ranking first among all acids, ahead of the second one by a large margin.

So hydrochloric acid is actually a very effective cockroach killer.

Pala—

With the splashing of hydrochloric acid.

The cockroaches panicked at first, and started to crawl around in the bottle.

But soon, their body surfaces were corroded by hydrochloric acid and cracks appeared.

In just a few minutes, these unlucky ones will be the last.

Death.

All loyal American cockroaches.JPG.

See this scenario.

Old Su suddenly shrank his pupils, and said in shock:

“How is this possible? There is poison in table salt?”

Xu Yun smiled slightly upon seeing this, but did not speak.

Old Su’s reaction was within his expectations, or to put it bluntly, this was actually one of his goals:

In ancient times when microcosmic cognition was almost zero, there was nothing more impactful than separating ‘very poisonous’ substances from the refined salt that was eaten every day.

When the next thing he did was finished, Old Su would inevitably ask him some questions.

And if there is no accident, 100% will involve the microscopic field.

With such an example that happened in front of me as evidence, some words are obviously easier to be convincing.

Then Xu Yun stored the produced hydrochloric acid, and picked up another thing that Lao Xu had prepared:

witherite.

Witherite is a kind of barium-containing ore, which is often used as acid decomposing witherite ore to produce barium chloride in later industries.

Xu Yun washed the witherites that had been ground into powder, picked up a small spoon, and threw them into the hydrochloric acid solution.

Half an hour later.

A bottle of mixed solution is prepared successfully.

Xu Yun began to add sodium hydroxide to it again—this is one of the products of the previous electrolysis. Although there are other cations in it, they are the target products themselves, so they will not affect the reaction process at all.

It took Xu Yun a lot of effort to make every link link up.

Well known.

In the witherite solution, the pH of complete precipitation of Fe3+ is 3.2, the pH of complete precipitation of Mg2+ is 11.1, and the pH of complete precipitation of Ca2+ is 13.9. (Paper reference 10.16283/j.cnki.hgkwyjg.1996.06.014)

Therefore, Xu Yun doesn’t need to care about the real-time data of the pH value at all, as long as he observes the precipitation changes in the reaction process and he’s done.

Another hour passed.

After adding sodium hydroxide dropwise and filtering.

A bottle of standard barium chloride solution is made.

At this point, the rest is very simple, that is

Coarse salt purification of the concept of junior high school.

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

The third step is to add soda, which is sodium carbonate.

This thing 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, Na2CO3—you can use PH test paper to observe the amount of hydrochloric acid in this process if conditions permit.

Then another hour passed.

A large group of precipitated sodium chloride crystals came out of the furnace.

Xu Yun weighed the doses and dissolved them in water.

that’s it.

A glass of normal saline with a standard concentration officially arrived in 1100 AD.

And the other side.

Looking at Xu Yun who was tinkering with the preparation of garlic injection, Lao Su finally couldn’t help it:

“Xiao Wang, why can salt water produce such highly toxic substances after such treatment?”

Note:

I don’t know if someone will say why it takes so much trouble to make salt. Let me tell you here, it’s not just for making salt

In order to make the following plots fit, you don’t know how tired I am when my friend is harassed by me.

Ask for a monthly pass, there are additional activities for the monthly pass.

It’s been 13 hours since I wrote at ten o’clock last night, and I had breakfast in the middle.

Please ask for a monthly pass.

In addition, I recommend a new book by a friend, who is also a newcomer like us, “Global Reincarnation: My Identity Is Questionable”.

It looks a lot like a mass-produced article, but it’s not what you think. For details, please refer to the title of the first edition of our book

(end of this chapter)