"No one can stop time! Therefore, whoever can't keep up with the development of the times will be eliminated. Jiang Shiyue does not dodge or look back.

"The Qing Dynasty will die because of self-containedness. This is 78 years, not 68 years, and the college entrance examination that has been suspended for ten years has been resumed. Our country has begun to establish diplomatic relations with beautiful countries, and 52 publicly-funded students have already gone abroad, do you still plan to live in the past?

Our chief went to visit foreign countries, and people's televisions, electromechanical refrigerators, and refrigerators have become daily necessities, and we have not even popularized electricity.

At present, the southernmost part of our country is already experimenting with a new economic system, and relevant policies will be introduced soon. Many of the professions that are now considered the best may be phased out. Some of the professions that everyone thinks are bad may become sweet and sweet in the future.

These styles of workwear that you criticize may be the trend of tomorrow.

Of course, you don't think so. So you are the first to be eliminated under the system of economic reform! ”

Huff.

Although many young workers in the factory think that Jiang Shiyue is right, they even think that the tooling she changed is very foreign and beautiful.

But in 78 years, the head factory also paid attention to seniority, and young people did not have much to say.

It's like Qiao Zhen throwing down the sentence "Don't do it yourself!" Turning to leave, the two eager girls also hurriedly followed, just because Qiao Zhen was their master.

Director Chen was in a dilemma, so anxious that he slapped his thigh, "What can I do?" ”

It was Jiang Shiyue who comforted him in turn, "Director Chen, don't worry! I promised to help you sell your clothes, and you will definitely be able to sell them. ”

Director Chen watched Jiang Shiyue lead Yang Yang away worriedly, not understanding where she got her confidence.

Could it be that she would change her own clothes?

Jiang Shiyue doesn't change her clothes by herself, but she knows people's hearts well and plans to learn how to fish with Jiang Taigong.

Back at the factory guest house where she settled, Jiang Shiyue didn't do anything and concentrated on accompanying Yangyang.

Yangyang is different from ordinary children, and is not interested in parent-child games.

Jiang Shiyue tried for a long time and found that he was most interested in mathematics. I taught him something about math.

Yangyang's ability to accept mathematics is even far greater than that of many adults, and he learns very quickly by drawing inferences from others.

This is just more than a month, and simple addition, subtraction, multiplication and division are already difficult for him.

Jiang Shiyue thought about it and began to teach Yangyang geometry and algebra.

She is not a professional teacher and has no systematic teaching materials, she thinks of wherever she talks, a hammer in the east and a hammer in the west, and she listens to it with relish.

It's a pity that Jiang Shiyue returned most of the things to the teacher, and there wasn't much to talk about in a hurry.

It's like when I was a child, everyone would recite a lot of Tang and Song poems, and when I really graduated from college and worked, how many could I memorize?

The only fortunate thing is that Yangyang is young like a blank piece of paper, and Jiang Shiyue's half bottle of water can be shaken casually.

After teaching mathematics, I will talk about physics, and after physics I will talk about chemistry.

Yang Yang was like a small sponge, quickly absorbing what Jiang Shiyue had taught.

Jiang Shiyue was tired of assigning some homework to Yangyang, and ran to the side to fan herself.

In the middle of summer, it was already so hot that it was difficult to sit still, and listening to the cicadas outside the window became more and more impetuous.

Jiang Shiyue wished there was an air conditioner and a refrigerator.

Even if you have an electric fan, you can do it.

Air conditioning is not realistic for the time being, even if Jiang Shiyue can afford it, she can't afford it.

At this stage, the electricity consumption of residents in the city is still unstable, and there are power outages every three or five times. In rural areas, most areas are not electrified.

There is an electric fan, which is about the same price as a bicycle.

Jiang Shiyue counted his small treasury. The last time it was sold on the black market, it was one hundred and twenty-one yuan, plus the remaining two hundred and eighty-two yuan and one dime and six cents from before, for a total of four hundred and three yuan and one dime and six cents.

In the past few days, I spent 28 yuan and a dime on daily necessities, stationery, and bus rides, and I still have 375 yuan and a dime left.

This money should be enough to buy an electric fan for Qiao Siye, but after buying the fan, he basically has to go bankrupt again.

It's too hard to make this money, and Jiang Shiyue is reluctant.

So what to do?

Jiang Shiyue walked around the room twice with a paper fan and snapped her fingers, "There you have it!" ”

provoked Yangyang to look up at her, with disapproval written in his eyes.

Jiang Shiyue sat opposite Yangyang, forcibly holding his little hand, staring at Yangyang with blazing eyes.

Yang Yang, who has always been unfazed, had an obvious dodge for the first time.

Of course, Jiang Shiyue refused to let Yang Yang leave, "Yang Yang, you are so smart, shall I teach you something else?" ”

Yang Yang didn't speak.

"Let me ask you, do you know how the ancients made ice without refrigerators? How did those dignitaries live a life of cold drinks and cold air in the summer? ”

Yang Yang's face was expressionless.

"The first one, of course, is to dig deep cellars and keep them warm. In the winter, put the ice in the ice cellar and store it for the next summer. This method has no reference value for us. ”

Yang Yang stopped pulling his hand back and looked back at Jiang Shiyue.

"The second option is to make ice from chemicals.

Do you know saltpeter? It is one of the raw materials for making gunpowder. Of course, gunpowder is not something we can touch, but we need saltpeter to dissolve to make ice.

The main raw material of saltpeter is potassium nitrate, which produces a lot of heat when dissolved in water. As a result, the water will cool down to freezing point, so that we can use ice. ”

Yang Yang's little face was obviously still a little confused.

Jiang Shiyue spread her hands, "I can't answer your questions." To tell you the truth, I used to watch a palace fight drama and learn it.

Gong Dou is a group of women who live in the palace and intrigue with each other all day for a man.

In that particularly popular palace fighting drama, there are iced fruits and ice kans at every turn. We...... My friend and I studied the ancient ice-making method out of curiosity. ”

In fact, Jiang Shiyue was living in college at that time, and it was very hot in the dormitory, although there was air conditioning, it was also open for a limited time, and it was often so hot that it was uncomfortable. Influenced by Huan Huan, the sisters in the dormitory suddenly wanted to make ice in the dormitory.

They bought some potassium nitrate online.

At that time, there was a student in the dormitory, and Jiang Shiyue didn't need to interfere in the matter of ice making, and she couldn't remember the specific process clearly.

Jiang Shiyue let go of Yangyang, took a piece of paper, and taught Yangyang while writing.

"First of all, consider the amount of heat that needs to be released when the water freezes in the summer.

Let's set the indoor temperature to 30°C, we are the standard atmospheric pressure, and the water temperature is about 25°C.

Water freezing can be divided into two parts: water cooling from 25°C to 0°C and then freezing and exothermic from 0°C.

Because Q=cmt. Specific heat capacity of water: 4.2×10³ joules/(kg·°C)

A liter of water is also a kilogram of water. Then to get water from 25°C to 0°C, you need to release 105 kilojoules of heat.

At 0°C, one gram of water freezes to release 80 calories, that is, 334.8 joules, we only take 334 joules, so one kilogram needs to release 334K kilojoules.

Therefore, it is estimated that water will release 439 kilojoules of heat from freezing at room temperature in summer.

Consider saltpeter next.

Potassium nitrate, the main component of saltpeter. The purity of industrial grade saltpeter can reach more than 99.0%. Let's leave impurities aside for now. Potassium nitrate heat of dissolution 34.89 kJ/mol.

In Jiang Shiyue's memory, the solubility of potassium nitrate at 20 °C is about 31.6 grams, so at 25 °C, the solubility is 35 grams, and the molar mass of potassium nitrate is 101 grams/mol.

So to absorb 439 kJ heat, 1270.8 grams of potassium nitrate are needed, and the density of potassium nitrate is 2.109 grams per cubic centimeter. That is, 602.57 cubic centimeters. ”

Jiang Shiyue threw down the pen and unconsciously began to bite her thumb.

This is not the right result.

It's not that it's a miscalculation, but it's unrealistic to throw potassium nitrate directly into the water.

Jiang Shiyue pulled her hair irritably, she remembered that the top student roommate in the dormitory had made ice?

Which step went wrong?

There was a knock on the door.