Chapter 378 Oxygen and Nitrogen
This experiment is not only of great practical significance, but also an excellent educational opportunity, so in addition to the participants Agatha, Sylvie, Chames, and Kyle Strayer, Roland took other members of the Witch Union, Carter, Iron Ax, and Barov all called over. In order to accommodate the twenty-odd people, the experiment location was chosen as the fifth laboratory with the largest space.
For the sake of the first attempt, the fractionation vessel was not made too large. It was about one person high and one meter in diameter, similar to a tower. The inside of the container is divided into three layers, the bottom layer is used for air intake, and the upper two layers are used for exhaust.
Before the separation began, Roland first gave a simple chemistry lesson for everyone, told them what might happen, and asked a few small questions by the way, so that everyone could find the answer by themselves-in addition to arousing the interest of the listeners, It can also greatly enhance the effect of teaching, which is also a common technique used by chemistry teachers.
"...Theoretically, when Agatha lowers the temperature inside the container, the air will gradually condense into a liquid, pass through the perforated partition, and drop to the bottom. So when you observe liquid accumulation at the bottom, let us know."
Since it is impossible to see directly, Sylvie has to observe through the container to describe the changes, so Roland explained in detail in this part.
Sylvie nodded suspiciously, "Can you really see the liquid appear? It can't be the water vapor in the jar, right?"
"Don't worry, liquid air is light blue, completely different from water vapor." Roland waved his hand, "And at that temperature, water vapor would have already solidified into ice crystals." Then he gestured to Agatha, "Then let's start."
"Wait...doesn't this hole at the bottom of the container need to be plugged?" she asked.
"Clog it later, otherwise there will be too little air in the tank, and no obvious changes can be observed." Since it was just an experiment, Roland chose the simplest way to inhale air—when the temperature in the tank drops rapidly, the pressure will increase. It will be lowered accordingly, so that the outside air will continue to pour into the tank. In conventional production, doing so is not worth the loss, because the air-conditioning will continue to be lost, wasting energy, but Agatha uses magic power, and the cooling efficiency is far higher than that of any refrigerator, so Roland didn't bother to prepare the air pump to inflate.
Agatha took a deep breath and pressed her hands on the fractionation tower.
Within a few breaths, there was a whistling sound in the air intake duct, which was the sound of rapid airflow. Layers of hoarfrost emerged around the nozzle at a speed visible to the naked eye, and continued to expand—the moisture in the air condensed rapidly under the overflowing low temperature, and attached to the outer wall of the container. Anna turned the black fire into threads, and cleaned up the ever-thickening ice crystals.
After a while, Sylvie said in surprise, "I saw liquid appear on the partition, but it was more white frost."
"The white frost may be the influx of water vapor, or it may be the crystallized carbon dioxide," Roland explained. "Considering the extremely low carbon dioxide content in the air, most of it should be water vapor."
In formal production, before the air is pumped into the fractionation tower, it must be dried first, otherwise the water vapor will easily block the layered plate and the exhaust hole after condensation, which will reduce the production efficiency.
About half an hour later, Sylvie reported that the bottom of the container had been filled with blue liquid, and Roland asked Soraya to block the intake pipe and seal it with a coating.
Next comes the critical warming up.
According to the different melting and boiling points of nitrogen and oxygen, nitrogen will reach the boiling point first, turn into gas and escape upwards, so as to realize separation. He neither remembered the specific value of this temperature, nor had any means to measure it at present, so he could only rely on Agatha to grasp it. Its specific manifestation is that the gas is discharged from the vent hole at the top of the fractionation tower, and the remaining liquid at the bottom will become more and more blue, which means that the purity of liquid oxygen is constantly improving.
Fortunately, Agatha is no stranger to the control of magic power. She precisely adjusted the cooling rate to make it rise slowly. After a while, Sylvie also observed the boiling phenomenon of the liquid surface. Bubbles began to appear in the coated pipe leading into the water, and Kaimo quickly collected several bottles of gas using the drainage method.
"Is this nitrogen gas?" Lily curled her lips and said, "You can't see anything at all."
"This is the first question I asked before," Roland asked, "How to prove that it is different from air?"
"Ignite," Tilly answered first. "Elementary Chemistry says that oxygen is needed for combustion. If it is another gas, it should instantly extinguish the burning wood."
"Just recool it into a liquid." Agatha said after thinking for a moment, "Didn't you say that nitrogen is colorless after liquefaction?"
"Or take out the remaining liquid in the container, and prove that the latter is pure oxygen, which can also prove the diversity of air components." Anna said.
The scene completely became a stage for Xueba to perform. One by one, the test methods were proposed and then discussed with each other. Only a few voices remained in the laboratory. Roland looked around and found that Nightingale, Andrea, Maisie and other witches, as well as the head of the city hall and chief knight Carter, all looked dazed. Iron Ax, commander of the First Army, maintained an expression at all times, probably no matter what he said, he would nod in agreement.
Well, Roland sighed in his heart, it seems that this chemistry class is a little bit beyond the outline.
If there are still people who can feel the joy of His Royal Highness, the only ones left are Kaimo Strull and Chames.
"Your Highness, this is really... miraculous," the young alchemist exclaimed, "You have proved the correctness of "Elementary Chemistry". I am afraid that no alchemist would have expected that even the air around us is so complicated. "
"With pure oxygen, is it possible to observe a more intense oxidation reaction? I have a lot of experiments that I want to do," Kaimo said excitedly.
Roland nodded, but another thought suddenly popped up in his mind.
Nitrogen is the most important raw material for the artificial synthesis of ammonia. It reacts with hydrogen under the conditions of high temperature and high pressure and an external catalyst to obtain ammonia. The latter can not only be used to make nitrogen fertilizers, but also to synthesize nitrogen oxides, thereby producing nitric acid. But for this process to be realized, there is still a lot of work to be done, such as air pumps, vacuum gas storage tanks, and a series of complex reaction equipment. Even if white paper can provide the function of catalyst, it will take trial and error.
Now that he has pure oxygen and nitrogen, why not just produce nitric oxide?
Indeed, the reason why the chemical industry chooses to use ammonia to produce nitric acid is that the reaction between oxygen and nitrogen is an energy-absorbing reaction, which cannot be carried out spontaneously, and requires an external supply of energy, such as electric discharge, which can be realized by heating the gas to thousands of degrees instantaneously through an electric arc. The reason why the soil is more fertile in places where thunder is frequent. Because of this, this method requires high equipment and consumes a lot of energy, so it is not suitable for formal production.
However, if there is an urgent need to increase production capacity, this production method is the most efficient, and does not even require a catalyst, only continuous discharge...or use other means to achieve the high temperature generated by the arc.
Roland naturally thought of Black Fire.
The heating efficiency of the black fire is no worse than that of the electric arc, and the burden on Anna is also extremely low. As long as the nitrogen and oxygen are purified and mixed in proportion and poured into a closed reactor, the nitric oxide can be continuously generated.
He decided to try it this way.
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