November 8th!

Overcast to light rain!

Lan Jie came to the test center to participate in the theory test of the semi-finals.

The full score of the semi-final theory exam paper is 100 points. The first question, the element inference question, says that metal A is often used for the protection of iron, A reacts with chlorine to get B, B undergoes a certain reaction to get C, and C undergoes a certain reaction...... The reaction has been the same until the new product is obtained, please write the chemical formula A~I.

Key clue: H2S is introduced into the hydrochloric acid solution of B to obtain a golden precipitate (commonly known as gold powder).

In recent years, with the continuous understanding of students' knowledge of inorganic chemistry in college, the elemental inference question has evolved from "skill examination" to "knowledge recitation", and even the words "memorize such and such a book, and be proficient in elemental inference", which makes people helpless and sad.

In this elemental inference question, as soon as a player with a good foundation in elemental chemistry sees gold dust, he can immediately deduce that A is Sn.

Is that really the case?

Yes, that's it.

Lan Jie knew that A must be Sn, so he took Sn as a starting point and quickly deduced SnCl4, SnCl2, and Sn(C6H5)4......

The first question belongs to the knowledge point crushing question, and if you remember the relevant knowledge points, you can crush the first question. Otherwise, it will be crushed.

There is only one question in this paper that is similar to the first question. The rest of the questions require not only sufficient knowledge but also flexible skills.

In the second question, it is said that there is a class of organic/inorganic hybrid thin film solar materials in the field of optoelectronic materials that are cutting-edge materials, which are composed of three kinds of ions, and the unit cells of the crystal have 4 C3 axes along the body diagonal, A is the apparent positive monovalent cation or group, and its fractional coordinates are (0,0,0). B is the cation of metal Pb2+, Sn2+ and other cations, and its fractional coordinates are (1/2, 1/2, 1/2). X is the halogen ions such as Cl-, Br-, and I-, and the fractional coordinates are (0,1/2,1/2), (1/2,0,1/2), (1/2,1/2,0).

Then the contestants are required to use the knowledge and skills of crystal structure to find a series of results.

'Is this thing a perovskite solar cell?'

Lanjie set this thing up to be a perovskite solar cell, and then began his deduction and calculation.

Whatever it is, Pauling's first and second rules apply.

'A and X together form a cube dense pile!'

'B is filled in an octahedral void made up of 6 X ions, so the coordination number of B to X is 6!'

'Calculate the negative charge around X as 1!'

That is, the positive and negative charges are balanced, there are no discrete coordination ions, and the structure is stable!'

'Yes, this thing is a perovskite solar cell!'

'Organic ions are used as cations of perovskite materials in organic/inorganic hybrid thin-film solar cells, and the power function affects their contact with direct contact materials, thus affecting the energy conversion efficiency of solar cells!'

'The crystal skeleton composed of inorganic ions can stabilize the structure and effectively reduce the loss of carriers, thereby improving the performance of solar cells!'

'It is found that the radius of A ions is in the range of 245~286pm!'

'There's something about this perovskite solar cell!'

Ranger continued to work on the following topic and came up with some insights.

Ding Ding Ding!

Submit the papers!

After the game, Qian Baoshan asked with concern: "Lan Jie, how did you do in the test?"

Lan Jie said with confidence: "Play normally, it's not a big problem." ”

"That's good, let's wait for the results of the theory exam. ”

"Mr. Qian, in the past few days of waiting for theoretical scores, I want to continue to improve my hands-on ability in chemistry experiments. ”

"No problem, I'll arrange for Teacher Qi to tutor you in your chemistry experiment one-on-one. ”

Under the arrangement of Mr. Qian, Mr. Qi, one of the experimental coaches of the chemical competition team, immediately implemented one-on-one chemical experiment counseling for Lan Jie.

On November 11, the scores of the theory test for the semi-finals were announced.

Rangier, 98 points!

I deducted 2 points!

After entering the semi-finals of various discipline competitions, why is it so difficult to get full marks?

To be reasonable, 98 points are also very high.

Lan Jie qualified for the semi-finals.

On November 13, the semi-final experiment was held.

This experiment is a conventional organic synthesis experiment, and Lanjie completed this organic experiment with conventional operations.

The full score of the chemical competition experiment was 50 points, and on November 15, the score of the chemical competition experiment was announced.

Lan Jie scored 47 points in the chemical competition experiment, and his total score in the semi-finals was 145 points.

In this year's mathematics, physics, chemistry and biology competition, Lan Jie all advanced to the national finals.

President Wang Yongjia convened a meeting of the heads of various departments and units in Yangzhong, and he gave the latest instructions at the meeting: "The time of the annual decisive battle has arrived! Please show the fullest spirit and the most professional technology to strengthen and strengthen the national finalists of the four major competitions of mathematics, physics and chemistry of our university! I hope that the number of national first prizes of our university this year will exceed that of last year." Students who are selected for the official list of the national team, I hope no less than one. ”

"We treat any student equally, and on the basis of treating a very small number of extremely special students, we can appropriately give resources beyond the scope of the norm. There is no doubt that Lan Jie, who also advanced to the four major competitions, is this kind of extremely special student. ”

A teacher asked: "In the national finals of the four major competitions, Lan Jie has the potential to create unprecedented achievements, and it is necessary to give Lan Jie unconventional resources during this critical time on the eve of the national finals." So President Wang, what are the upper and lower limits of unconventional resources?"

Principal Wang said categorically: "On the premise of not violating the law and school rules, any resources that are conducive to Lan Jie winning the National One Award can be given to him." ”

After the meeting, the leaders returned to their respective posts and conveyed the spirit of President Wang's instructions.

Lan Jie, who is actively preparing for the national finals of the four university science competitions, shuttles between the competition classrooms and laboratories.

"Mr. Qi, there is a type of chemical experiment that is particularly interesting, that is, the use of simple and easily available raw materials, through ingenious chemical operations, to produce products with wonderful chemical properties. Can you teach me more about chemistry experiments like this?" asked Ranger his request.

Teacher Qi asked, "Lan Jie, will this help you win the first prize in the national competition?"

Lan Jie said with certainty: "Yes, it will help me to win the first prize in the competition." ”

"Chemistry is an experimental science, using simple and easily available raw materials to produce chemical products with special and wonderful chemical properties, and there are many chemical experiments of this type. Without further ado, let's get started. Mr. Qi pulled out a list of simple and wonderful chemical experiments that he knew.

Under the careful guidance of Mr. Qi, Lan Jie did these chemical experiments one by one, and he benefited a lot, and his cognition of chemistry and his hands-on ability in chemical experiments continued to be strengthened.