Vol 2 Chapter 849: Exam (below)!

"Question 1: Put a certain amount of anhydrous alcohol and oxygen in a completely closed container to ignite, the reaction produces carbon dioxide, water vapor and an unknown substance X. The mass of the substance before and after the reaction is measured, and the anhydrous alcohol is 4.6g and 0g, oxygen is 8g and 0g, carbon dioxide is 0g and 4.4g, water is 0g and 5.4g, substance X is 0g and mg, the value of m is ______, and the molecular formula of substance X is ______."
(Note, in order to facilitate future teaching, Li Zexuan unified the unit at the forefront of the four textbooks, but this is only a written unification, and the actual unification will depend on the joint efforts of the teachers and students of Yanhuang Academy in the future)
Although I have been prepared for the difficulty of the exam, the first question is such a practical application plus calculation question, which still surprised Wang Ji. Shouldn't I first test the basic concepts?
But this question is mainly about the law of conservation of mass in the process of chemical reactions. After a little calculation, he got the correct answer.
At this time, he couldn't help but feel fortunate in his heart. Fortunately, he also studied new maths, otherwise, how could it be so fast?
"In the second question, put two glass cups A and B on the two scales. The glass cups contain dilute sulfuric acid with different qualities but both contain 9.8g sulfuric acid. It is known that the glass cup A is heavier than the glass glass B. After putting equal masses of iron and zinc into the two glass cups A and B, the balance is kept in balance, and the maximum quality difference between glass A and B glass before the reaction is OR."
(Note: The balance has existed in ancient times. It was produced earlier. By the late Spring and Autumn Period, the manufacturing technology of balances and weights was already quite sophisticated. The beam was made of bamboo, the silk thread was the button, and the two ends were hung. A copper plate. Later, because the balance was troublesome to weigh, it was changed to "Quan", and the balance was used when weighing small objects)
Although Wang Ji had never seen such things as sulfuric acid and zinc, he still knew their chemical reactions thoroughly, but how did this question look more perverted than the previous one? You should also use the equation knowledge in new formulas, right?
Wang Ji's heart suddenly began to gallop, and he had to do some research on new mathematics. Otherwise, even if his "Chemistry" textbook was memorized and understood, he would have to kneel when he encountered this test paper!
However, although Wang Ji has some research on new maths, he is far from proficient. After solving a problem, he is already sweating profusely, just like running ten miles.
After finishing the second question, Wang Ji couldn't help but raise his head, and with his somewhat resentful eyes, he glanced at Li Zexuan and said in his heart: Does the old man have hatred with your kid? It's just a question. Is it necessary to make it so difficult?
It's not that he is hypocritical, but in a strict sense, Li Zexuan's question is somewhat "super-class". Moreover, all the test questions are biased towards practical applications. It is basically difficult to get good results just by reading books!
"Oh, no matter how difficult it is, you have to fight! This bet can't be lost!"
Although he only stayed in Yanhuang Academy for more than a month, Wang Ji felt that he had completely liked it here. Not only did he like the environment, facilities, wine and food, he also liked the atmosphere of Yanhuang Academy, which was positive. An atmosphere of unity and progress!
He doesn't want to leave!
Desire to survive, this can be regarded as another desire to survive!
The strong desire to survive has made Wang Ji's mind more sober than ever, and his thinking has become more active. Although most of the test papers are questions he has never seen before, he can always find ideas for solving problems. After breaking through all the way, Wang Ji finally came to the last question when half an hour before the end of the exam.
This is a question and answer, "37.2g of a mixture composed of sodium carbonate, sodium bicarbonate, calcium oxide and sodium hydroxide, dissolved in enough water and fully reacted, the solution contains calcium ions, carbonate ions, and bicarbonate ions. Converted into precipitation, the water in the reaction vessel was evaporated to dryness, and finally 39.0g of white solid was obtained. What is the mass of sodium carbonate in the original mixture?"
The sequelae of breaking through all the way and performing supernormal performance is brain pain. At this moment, after seeing this last big issue, Wang Ji felt that his head was about to blow up! Because many substances in this question can interact with each other.
In fact, for Li Zexuan, who has received modern higher education, this question is not difficult at all, because it involves multi-step reactions and multi-material cross-reactions (calcium oxide reacts with water to form calcium hydroxide, calcium hydroxide It can react with sodium carbonate and sodium bicarbonate). Just combine multiple chemical reaction formulas into one and balance them. After obtaining a total chemical reaction formula, the whole problem will be solved without any difficulty. .
But for Wang Ji, a beginner of "Chemistry", he obviously does not know this method, so what should he do? He must take this question!
After thinking about it for a long time, Wang Ji didn't think of a very clever and simple method. He gritted his teeth and turned his mind. He decided to use the most stupid way to solve this problem, that is, to use the equation method.
"Isn't there more unknowns? It's okay, solve! The old man doesn't believe it, I can't solve it today~!"
Wang Ji secretly said viciously.
At the same time, he couldn't help feeling, whether this is the "Chemistry" exam or the "Mathematics" exam? He used three draft papers for calculations!
Fortunately, he used a pencil given by Li Zexuan. If he used a brush, Wang Ji felt that he didn't have to take the exam, and he would be exhausted from polishing the ink~!
"Clang clang clang~!"
"Okay, time is up, Mr. Wang, please stop writing~!"
At four quarters after Shen Shi, the academy's gongs and drums sounded, and Li Zexuan immediately got up and said.
Wang Ji just finished writing the last word at this time, and he let out a sigh of relief. He thought that an hour and a half was more than enough, but now he doesn't even have time to check, so he has to hand in the paper.
"Haha~! Wang Wugong, how did you get on the test?"
As soon as Wang Ji handed in the paper, Yan Silu immediately asked.
In that tone, I don't know whether it is gloating~EbookFREE.me~ or worrying.
"No way, no way! I'll talk about other things later, the old man has a headache now, and I have to go back and rest~! Shanchang, Wenji, Kong Gui, I'll leave first~!"
Wang Ji wrinkled his brows, squinted his head, stood up and said with a painful expression that he was a little over-exerted in this exam.
"Mr. Wang is unwell? Would you like a kid to call a doctor for you?"
Li Zexuan asked with a worried look. He didn't want to destroy Wang Ji, a "genius" because of an exam.
"No, the old man just feels a little tired, after a nap, it should be no problem~!"
Wang Ji waved his hand.
………………………
Second!
The third one is late, let's see it tomorrow morning!
(End of this chapter)