Into Unscientific

In the 21st century.

Compared with hand rubbing generators, the concept of electrolysis may have a wider spread.

Especially the electrolysis of saturated salt water, this is a basic chemical reaction that cannot be further 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 electrolysis reaction occurs, some anoxic acid salts of active metals will generate alkalis at the cathode.

Oxygenates of inert metals 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 normal, in fact, two carbon rods have no effect.

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

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

Therefore, 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 what Xu Yun considers is

salt bridge.

In the courtyard.

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

"My lord, where is the white crystal block I 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 to open the package, carefully identified it, and affirmed:

"Yes, it is indeed saltpeter.

I heard the old man speak with a Hexi accent, presumably the saltpeter was 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 government.

Later, he had no choice but to show the waist badge of the county government, and invited a government servant on the street to testify, and the other party was willing to sell him some crystals, and the price was not low. "

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

"Saltpeter of this quality is quite expensive, but it can save a lot of trouble."

When Xu Yun saw iced sour plum juice in the sour plum shop earlier, 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.

Therefore, although Xu Yun was not sure that the other party must have saltpeter in his hand, he was almost seventy percent 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 and sodium hydroxide generated by the electrolysis of salt water from reacting in the electrolytic cell to the greatest extent, thereby promoting the production of chlorine gas.

The preparation of potassium nitrate is also very simple:

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

Heating, evaporating and concentrating, KNO3 crystals can be obtained after cooling.

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

After a lot of preliminary work is ready.

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 somewhat cloudy.

Xu Yun looked at Old Su:

"Sir, please bring the gauze."

Although Old Su didn't quite understand his intention to operate on Xu Yun, 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 cover.

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

At this time, the donkey had already fully charged the clockwork, 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 was 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's preset number of rotor slots is 2, and the speed is 300 revolutions per minute. The calculated accurate value is 15.7, which should be 16 revolutions logically.

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 ready, 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.

Incidentally, here.

This concept seems to be easy to understand, but it specifically involves the concepts of overpotential 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 category, the discharge sequence of hydroxide in water is in front of the oxyacid, so the oxyacid cannot be discharged.

But in fact, because of the existence of overpotential, a side reaction of generating H2S2O8 will occur during the period, which exceeds the standard electrode potential of 2.01V, forming an overpotential situation.

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

Realize and return to the original place.

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

The cathode generates hydrogen gas.

The anode generates chlorine gas.

The resulting gas escapes and is collected by a glass tube in 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 dissolves with the 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:

Hydrochloric acid can also be obtained by dissolving the chlorine gas produced by the electrolysis reaction in water, but this reaction produces a mixed solution of chlorine and water.

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

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 and packaged the hydrochloric acid.

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

"Master, can you get someone to catch some cockroaches?"

"Cockroach? Why do you want that thing?"

"Little people have their own uses."

Lao Su saw a lot of Xu Yun's strange operations today, so he didn't ask any more when he saw what he said. He glanced at Mr. Xie who was beside him, and ordered:

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

Mr. Xie nodded, turned around and arranged for the staff.

Mentioned long ago.

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

In addition, the sanitation level of the Song Dynasty was much lower than that of later generations, and it was summer again, so cockroaches could naturally be seen everywhere.

So not long after, Mr. Xie came 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 the American cockroach again, old trick.

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

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

But cockroaches are 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.

Therefore, 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.

Died of anger.

All loyal American cockroaches.JPG.

See this situation.

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

"How is this possible? The salt is actually poisonous?"

Seeing this, Xu Yun smiled slightly, 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 toxic' substances from the refined salt that was eaten every day.

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

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

With such an example that happened before 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 to acidify 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 dropped them into the hydrochloric acid solution.

After half an hour.

A bottle of mixed solution was 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 really took Xu Yun a lot of effort to make every link closely linked.

well known.

In 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 didn't need to care about the real-time data of the pH value at all, as long as he observed the precipitation changes in the reaction process, he was 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,

The crude salt refinement of the junior concept.

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.

These are ubiquitous in the glassmaking industry to remove calcium ions and barium ions from BaCl2.

Finally, add HCl to remove excess NaOH, Na2CO3 - if conditions permit in this process, you can use PH test paper to observe the amount of hydrochloric acid.

Then another hour passed.

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

Xu Yun weighed the doses and dissolved them in water.

that's all.

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

And the other side.

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

"Xiao Wang, why can the salt water produce such a highly poisonous substance after such treatment?"