"Here comes the water!"

With a shout. I saw several classmates guarding a classmate who was only wearing pants and was wet and ran over quickly.

Li Zhen nodded to the classmate: "It's hard work." ”

Then he took the water from the deep well in a bottle, poured it into a beaker, and placed the beaker filled with well water in a basin filled with saltpeter:

"Saltpeter is mainly composed of nitrate, and its chemical name is also called potassium nitrate. In fact, after being proportioned with ammonia, it will become ammonium nitrate...... Mainly talking about saltpeter, saltpeter is easily soluble in water, the reason why you keep stirring is because saltpeter will continue to absorb the heat in the water in the process of dissolving in water. If the temperature of the cold water in this basin is 15 degrees, then after you keep stirring it here, it is already close to freezing. ”

Hearing Li Zhen say this, Qi Dengming, who was sweating profusely, reached out to touch the water in the basin, and quickly retracted his hand as soon as he stretched out his hand, and shouted in surprise: "It's so ice." Really, really cooling down. It's cooling down. ”

"I'll touch it too."

"Don't squeeze, I'll touch it too."

"Don't touch it, your body temperature will make the water warm, don't spoil the test." Xu Shenxue yelled.

The excited students immediately retreated, and then Xu Shenxue also touched his hand in the water, and shouted in surprise: "Hey, it's really cold." I'm afraid it's already 0 degrees, right? ”

Qi Dengming asked Li Zhen again: "Then you knew that adding saltpeter to the water could reduce the temperature of the water, why did you take the extra step to get deep well water and put a new cup into this basin?" ”

Li Zhen said: "In the process of your constant stirring, although a large amount of saltpeter is dissolved, the water temperature is lowered. But at the same time, it is constantly destroying the equilibrium state in the water molecules, and it requires more pressure, so it is not easy to freeze. In fact, even if the water in this basin freezes, it is undrinkable. So, if we compare this basin to ...... Likened to a closed container that can be cooled. Then this cup of well water in the basin is the thing that will really turn into ice. ”

"Why?"

"The temperature of the water in the basin has become extremely low. This beaker will pass through the beaker to the deep well water in the beaker, thus continuing to reduce the temperature of the deep well water. The temperature of the deep well water is constantly passing and when it reaches freezing, it freezes. ”

"So what now? Stirring all the time? ”

Qi Dengming asked.

Li Zhen smiled and shook his head: "No need." It has absorbed the heat sufficiently. Now all you need to do is cover the beaker with paper or plastic. Then cover the basin with a wooden board, put a quilt on the wooden board, cover it for 30-60 minutes, open it, and the water in the beaker will complete the process of freezing. ”

"Huh? Why cover the beaker with plastic sheet? ”

"Prevent the temperature in the cup from slipping. The beaker needs to be kept cold continuously. ”

"Then why do you have to cover the basin with a quilt? Didn't you say that it was going to freeze? Doesn't that heat up the water when you cover it with a quilt? ”

Li Zhen smiled, did not answer the question, and left Youyou. It's far more useful to tell them how it works than to show them some way.

Maybe it's amazing that sodium acetate supersaturated solution freezes. But understanding the slow freezing of nitrates is more useful for their pioneering thinking in chemistry.

After Li Zhen left, the chemistry teacher slapped the student on the head angrily: "If you don't learn something that doesn't have skills, don't talk too much, no one will treat you as a dumb person." ”

The student's face was full of grievances: "What did I say? ”

"You don't know how to learn, cover this basin with a quilt, and ...... Why did you heat up the water? ”

The student said sincerely: "I really think Li Zhen is wrong about this. That's what it was, the temperature in this pot is so low. You also have to cover it with a quilt to keep it warm, isn't that the opposite way? ”

"You...... You...... You don't know how to learn! ”

The chemistry teacher was so angry that he was about to vomit blood: "How did I teach you such a thing?" ”

"Teacher, am I not right?"

"Hahahaha."

The students around him laughed wildly, and at first I thought that this classmate was funny. Seeing that he hadn't reacted yet, he felt inexplicably poked at the point of laughter.

If you think about it carefully, it seems that there is nothing wrong with it, but if you cover the quilt with water, won't it be warmed? Wouldn't it be warmed up if you cover the ice with a quilt? Well...... It seems to make some sense.

Some students brought their own quilts and covered them on the basin. A group of teachers and students stood aside and waited anxiously.

Xu Shenxue kept frowning: "Is the time up?" ”

He wants to see the results more than anyone else.

"Headmaster, it's only been ten minutes."

"Why does time pass so slowly?"

“……”

"Is it time?"

"It's only been twenty minutes."

“……”

"Half an hour has come."

"Quick, lift the quilt."

Everyone in the chemistry lab gathered around, and when the quilt was lifted, they only saw a faint white smoke coming out of the basin. It's a chill.

As the quilt was lifted, it seemed that the temperature in the entire laboratory had dropped, and I wonder if it was a psychological effect.

But I saw that in the center of the basin, in the beaker, half an hour ago it was a cup of deep well water, but now it was all solidified into a full cup of ice. The ice was constantly bubbling cold, and the smoke was curling.

"Ahh

"It's really freezing!"

"This ...... This is edible ice. ”

"It's just autumn now, and it's so hot, that there really is ice that only appears in winter?"

"Saltpeter...... Isn't that something that makes bombs? It was able to freeze the water. ”

"I seem to have learned an amazing science. This...... After that, the summer will be blessed. ”

"Alas, Li Zhen is really Li Zhen, nothing can make it difficult to get him."

“……”

Xu Shenxue stretched out his hand and touched the cup of ice, only to feel the cold to the bone, this is real ice. He reached out again and touched the water in the basin, but the water in the basin was still at that temperature, unchanged. I can't help but be full of doubts, as if I have figured out something, and as if I have ignored something.

His eyes became solemn, and he immediately said aloud: "Make today's story into a book." Write down in detail the freezing of sodium acetate supersaturated solution and the way saltpeter freezes. Write out every principle and every word that Li Zhen said in detail. When it is printed, it is important that every student in the Department of Chemistry has a copy. ”

"Yes, Headmaster."

"Of course, I have to ask Li Zhen for advice. It's his patent. ”

"Yes, Headmaster."

“……”

Walking out of the teaching building, Xu Shenxue felt a little depressed in his heart, why did Li Zhen have such a strong knowledge.

"As Qian Mao said, putting Li Zhen in college for six years is really ...... What a waste of six years. ”

"Well, but how can I help him? He never asked anything of me, and he never said what he thought about the future. ”

"The phoenix fell in the chicken coop, Li Zhen, Li Zhen, you should fly to a wider sky."

Xu Shenxue's heart was full of grotesque thoughts, and he felt more and more that he had wronged Li Zhen's child......

In the separate dormitory, Qi was stunned and ran over from the teaching building in surprise: "Hahaha, it's really frozen, you're too powerful." ”

Li Zhen, who was reading a book, smiled: "Nothing so powerful. ”

"It's amazing. How do you know? Who taught you all this? ”

Li Zhen suddenly shook his whole body, and the book in his hand fell to the ground.

His eyes were full of incomparably shocked, incomparably puzzled looks, and he muttered sadly:

"yes, how do I know? Who taught me? These things...... Where did I learn that? ”

"Was it someone very important who taught me? Who is she. Who the hell is she. ”

Suddenly, with a pain in his heart, Li Zhen hurriedly took out the piece of paper in his arms and kept murmuring: "Zhang Zhi...... Chapter to. Why am I so afraid that I will forget these two words? ”

"Qi was stunned."

"What for?"

"Help me find a needle."

"What are you doing?"

“……”