Redox Reaction 1 Lecture Notes I. Textbooks
1, the position and function of this section
This section is arranged in the second chapter of 1, the textbook required by People's Education Press, the new curriculum standard. As far as the subject content is concerned, it is the beginning chapter for students to understand chemistry, and it is the link and bridge between compulsory education chemistry and senior high school chemistry, which plays an important role in developing students' scientific literacy and guiding students to learn senior high school chemistry effectively. Redox reaction is an important theory in middle school chemistry, and it is also a hot spot in college entrance examination. At the same time, it is very important to establish the viewpoint of energy in chemical reaction. Therefore, this part is one of the key points of chemistry teaching in senior high school.
2. Teaching objectives
1) knowledge and skills
Learn to analyze redox reaction from the viewpoint of valence and electron transfer, and deepen the understanding of redox reaction.
2) Process and method
From narrow definition to broad definition, from simple to complex, the essence of redox reaction is revealed.
Cultivate students' inquiry ability with "problems" as the main line; By designing experiments, students' inquiry spirit is cultivated.
3) Emotions, attitudes and values
(1) Cultivate students' learning quality of positive thinking and exploration by creating problem situations.
(2) Educate students in dialectical materialism, such as the unity of opposites and seeing the essence through phenomena, to help them establish a correct view of nature.
4) Emphasis and difficulty of teaching
Understanding redox reaction from the viewpoint of valence fluctuation and electron transfer.
Second, talk about learning.
Students' knowledge: Junior high school students have learned the knowledge of electron gain and loss, valence and redox reaction from the perspective of oxygen gain and loss, but it is not systematic. Student's ability: Through one-year chemistry study in junior high school, students have certain ability to ask questions, analyze and solve problems. However, students are used to passive learning and cannot actively participate in the process of knowledge acquisition.
Third, oral teaching methods
Students' thinking in class often begins with the presentation of tasks or problems, that is, "no anger, no power, no anger and no resentment." In this class, I take the "problem teaching method" as the leading factor and integrate various teaching methods to complete the task. By setting up obstacles and doubts, students are always faced with thorny problems and contradictions that need to be solved, prompting them to participate in teaching and using what they have learned to explore and solve various new problems, so that students are in an "angry" and "depressed" state.
Fourth, the methods of speaking and learning
Constructivism holds that "learning is based on the growth of existing experience, and it is a balanced process composed of assimilation and adaptation". On the basis of understanding redox reaction from the perspective of oxygen gain and oxygen loss, under the guidance of teachers' questions, students actively think and explore independently, and rise from narrow understanding to broad perspective of chemical valence fluctuation and electron transfer.
Fifth, talk about the teaching process.
[Introduction to the new lesson] Projection: the change of the surface color of the cut apple; Iron nails rust; Dry batteries make small bulbs glow.
Question: Do you know how they work?
Introduce new lessons with situational questions to stimulate students' interest and their awareness of inquiry.
[Review old knowledge]
【 Question 】 In the reaction of c+2cuo=co2+2cu, analyze the reaction of substances from the perspective of oxygen gain and oxygen loss?
[Question] Is it necessary for oxygen to participate in the redox reaction?
【 Question 】 The following are two positive and negative examples of redox reaction. Please summarize the essential characteristics of redox reaction?
[projection]
Example 1: H2+CuO = copper +H2O (redox reaction)
Example 2: Fe+CuSO4 = = Cu+FeSO4 (redox reaction)
Example 3: 2 Na+Cl 22 NaCl (redox reaction)
Example 4: H2+Cl 22 HCl (redox reaction)
Example 5: 2 HCl+CaCO3 = = CaCl2+CO2+H2O (non-redox reaction)
Example 6: 2 NaOH+CuSO4 = = Cu (OH) 2+Na2SO4 (non-redox reaction)
Through students' analysis and induction, we can understand the redox reaction from the perspective of chemical price.
【 Question 】 Can the reaction of c+2cuo=co2+cu be analyzed from the perspective of oxygen gain and oxygen loss, and the relationship between the rise and fall of valence and redox reaction can be obtained?
[Question] Why does the valence of elements change in the redox reaction?
[experimental inquiry]
Experiment 1: Insert zinc sheet into copper sulfate solution.
Experiment 2: Connect an ammeter between zinc sheet and carbon rod and insert it into cuso4 _ 4 solution.
[question]
1. Observe the experimental phenomenon and write the reaction equation.
2. What caused the current in Experiment 2? Why is there a steady stream of electrons?
2. Through the above experiments, what do you think is the reason for the change of valence in redox reaction?
Although the students have not learned the knowledge of primary batteries, they can realize that the essence is the same from the phenomenon. Then on the knowledge of current and electron gain and loss in junior middle school, let them realize that there is electron transfer in the reaction and understand the essence of redox reaction.
The animation shows the electron transfer in the redox reaction.
Intuitive teaching makes the microcosmic world visible.
[Transition] Next, from the microscopic atomic structure,
Understand the relationship between electron transfer and redox reaction, and understand the two forms of electron transfer-gain and loss and deviation.
Take the reactions of sodium with chlorine and hydrogen with chlorine as examples.
Projection and interpretation
At this point, students' understanding of redox reaction is strengthened in three levels.
【 Question 】 Discuss the relationship between redox reaction and four basic reaction types.
[consolidation exercise]
The reaction of substances in example 1, 2, 3 and 4 is analyzed from the point of view of valence fluctuation and electron transfer.
[Teaching reflection]
The teaching design of this course is completed according to the concept learning process. The related theories of "problem teaching method" and "discussion method" are used in the design. Through a series of well-designed questions, students are guided to learn through inquiry and discover through inquiry. The key to teaching is to guide students to actively participate in learning, deepen and broaden the knowledge learned in junior high school on the basis of discussion, and rebuild students' existing knowledge system and network.
Lecture Notes on "Redox Reaction" 2 i. teaching material analysis
"Redox reaction" is the content of the third section of the second chapter of the new chemistry textbook for senior one in People's Education Press. For redox reaction, analyze and understand it from the point of view of oxygen gain and oxygen loss in junior high school; The compulsory chemistry course 1 requires that on the basis of junior middle school chemistry, we can understand redox reaction and common oxidants and reductants from the viewpoint of valence fluctuation and electron transfer. Through the study of subsequent courses, such as the study of metals and their compounds, nonmetals and their compounds, students are required to have a more specific understanding of redox reaction before they can deeply understand the relevant knowledge of redox reaction. This lesson is not only to review the basic types of reactions in junior high school and the important knowledge of redox reactions, but also to pave the way for further study of redox reactions, and it is also an important link to contact the knowledge of elemental compounds in the future. It played a connecting role. The knowledge of redox reaction is an important theoretical knowledge of high school chemistry, which is not only the teaching focus of this chapter, but also the teaching focus of the whole high school chemistry.
Second, the teaching objectives
1, knowledge and skills: master the method of analyzing redox reaction from the point of view of valence fluctuation and electron transfer; Learn to judge redox reaction from the viewpoint of valence change and electron transfer; Understand the nature of redox reaction.
2. Process and method: It experienced the gradual and in-depth development process of redox reaction from the initial oxygen gain and oxygen loss characteristics to the superficial phenomenon of valence fluctuation to the essential reason of electron transfer. Through the analysis of the characteristics and essence of redox reaction, learn to think from the outside to the inside with a dialectical point of view.
3. Emotion, attitude and values: Through the understanding of the opposition and interdependence between oxidation and reduction, we can deeply understand the embodiment of the law of unity of opposites in natural phenomena and establish correct views and methods to learn chemical knowledge.
4. Setting of key points and difficulties:
Emphasis: Understanding redox reaction from the viewpoint of valence fluctuation and electron transfer.
Difficulties: Analyze the redox reaction from the viewpoint of valence fluctuation and electron transfer. Students master the concept of redox reaction and the relationship between unity of opposites.
Third, the teaching process
The teaching content of this class is very difficult, and it is not so easy for students to master the essence of redox reaction. Therefore, we must carefully design teaching methods, strive to explain things in simple terms, and mobilize students' thinking enthusiasm, so that they can actively participate in teaching activities and become the main body of learning. Therefore, I use the "problem-solving method" teaching to make students think, discuss and summarize through design-driven and interlocking problems, and with the help of multimedia teaching methods, I abstract the micro-process into a visual micro-macro, and gradually guide students' thinking direction in the process of solving problems.
The design of the problem is completed by interlocking the following problems.
Question 1: Let students recall the oxidation and reduction reactions in junior high school and give some typical examples.
According to the knowledge of junior high school, students judge oxidation and reduction reactions from oxygen gain and oxygen loss, and their answers may have many reactions. At this time, the teacher selected two typical reaction formulas for analysis. For example: But the oxidation reaction and reduction reaction are introduced separately in junior high school, so I then let the students discuss:
Question 2: For example, are the oxidation and reduction reactions carried out independently?
Through discussion, students can easily find that reduction reaction and oxidation reaction coexist, and oxygen will be lost if there is oxygen. It is not appropriate to artificially separate the two processes that occur at the same time in a reaction, nor can it reflect the essence of this kind of reaction. Therefore, we should constantly improve, deepen our understanding of various problems, and study with a scientific attitude. This problem not only deepens students' understanding, but also permeates dialectical materialism education. Teachers can also take the opportunity to introduce new lessons and summarize the concept of redox reaction from the perspective of oxygen gain and oxygen loss.
The above problems can be said to have laid a solid foundation for the introduction of new courses. In the process of solving these problems, students not only reviewed the knowledge of junior high school, but also mobilized the excitement of students' thinking, so that the' learning' of the new curriculum originated from junior high school and was higher than that of junior high school.
Question 3: Mark the valence of each element in the above reaction, and observe whether the valence changes and whether the change is regular.
Through practice and observation, it is not difficult for students to find that the reaction of increasing the valence of elements contained in a substance is an oxidation reaction, and the reaction of decreasing the valence is a reduction reaction. At this time, the teacher emphasized that any chemical reaction in which the valence of elements rises or falls is defined as redox reaction. Then let the students analyze:
Question 4: Is it a redox reaction without oxygen gain or loss?
From the analysis, students can know that although there is no relationship between oxygen loss and oxygen gain, the valence has risen and fallen, so it is also a redox reaction. It can be seen that the redox reaction defined by valence fluctuation greatly expands its connotation.
The transition of redox reaction and its related concepts from valence fluctuation of elements to electron transfer is the sublimation of its concept, the process of understanding its essence, the key link in teaching and learning, and the difficulty in teaching. I then asked:
Question 5: What causes the valence of elements to rise and fall in the redox reaction? That is, what is the essential attribute of redox reaction?
In the teaching of this process, I will make full use of students' existing knowledge to find out the internal relationship between the numerical value of valence, positive and negative values and the electron gain and loss of atoms. This paper makes full use of the advantages of multimedia to animate the reaction between chlorine and sodium metal, and the reaction between chlorine and hydrogen, and visualize the electron transfer during the formation of sodium chloride and hydrogen chloride. In this way, abstraction is concrete, and micro is macro, which greatly reduces the difficulty of students' understanding and imagination, and also successfully breaks through the difficulties.
At this point, the teaching task of this lesson has basically been successfully completed. In order to consolidate the knowledge learned in time, teachers can ask: among the four basic reaction types learned in junior high school, which reaction types are redox reactions and which ones are not. Explain and explain the students' answers.
Fourth, teaching reflection.
Looking back on the teaching of this class, I connected the whole class through five interlocking questions. In the process of thinking and discussing these problems, students cooperate with many senses at the same time and use a lot of information comprehensively. In the process of solving problems, they experienced the process of knowledge acquisition and learned the methods of abstract thinking and logical reasoning. Teachers play a leading role in it, students' subjectivity is fully reflected, and the concept of "all for students' development" in the new curriculum is fully implemented.