Reflection on the teaching of chemical balance

Part 1: Reflection on the teaching of chemical balance

Changchun Middle School Teaching Open Week, I went to a high school review open class entitled “Chemical Balance”. After class, I feel a lot. Chemical equilibrium is an important chemical concept. The concept of chemical equilibrium is relatively abstract, and the establishment of a chemical equilibrium viewpoint is also difficult. "Chemical balance" is the content of the compulsory block of high school chemistry textbook. It is one of the important theories of middle school chemistry. It is the basis for learning ionization balance, hydrolysis of salts, hydrolysis of halogenated hydrocarbons, hydrolysis of esters, and learning of many knowledge. An important guiding role. It is the biggest gain of the classroom to enable students to achieve an easy-to-understand teaching effect, so that the establishment of a clear chemical balance is the key to the success of this section.
The main line of my teaching in this lesson is: 1. First, instill a chemistry mind into the students, that is, what is the problem that chemistry needs to solve. I cited the example of industrial ammonia synthesis, that is, how to correctly understand a chemical reaction, proposed four words "quality" - qualitative change, the reactants can produce products; "quantity" mass, the amount of matter; "energy" energy Changes, ie endotherms and exotherms; "effects" - efficiency, effects, ie chemical reaction rates and chemical equilibrium problems. In order to introduce new lessons. 2. Review the chemical equilibrium knowledge points, suggest the definition of reversible reactions, and the characteristics of reversible reactions. 3. Starting from the reversible reaction, combined with the images often appearing in several college entrance examinations, the concept of chemical balance is proposed. And students have summarized the characteristics of chemical balance. 4. Break through the difficulty of this lesson, the criterion of chemical balance. 5. Class exercises to consolidate knowledge points.
I have been in the third year of review for more than two months, and I feel that I have summed up my own review method. It comes down to the following: "Diagnostic Exercise"----"Review of Knowledge Points"-----"Into the College Entrance Examination, Appreciation of the College Entrance Examination"-----"Difficult and Breakthrough"------"Classroom Exercise". After more than two months, I feel that the effect is good, but it also reveals some problems, that is, students are not active enough in the classroom. When the third year is a review class, the students already have a knowledge of knowledge. It used to be normal, but after listening to the master's lesson, it was not like this. The teacher's classroom is full of so-called "humanistic care". The teacher-student cooperation is very good. The student's subject status is very prominent, and many students take the initiative to raise their hands to answer questions. This is not in my class. During this time, I was also rethinking this question, and I also consulted many experts and teachers in the preparation group. The main reason is that I still talk too much about myself. I am afraid that students will not, and I am afraid that students will miss some knowledge points. However, it is neglected that this is a review class. Students have already mastered some simple and basic knowledge points through self-preparation and review. Therefore, it is normal to be uninterested.
In fact, after the last class of “Sulfur and its compounds” in the group, I combined my many teachers’ opinions and I also adjusted myself and reflected on classroom teaching. Let the students speak more in the classroom, and they are just reminding, guiding, and commenting. Obviously, I can feel the interest of the students, and it is very high. When some students answer questions, other students can listen more carefully and then add. The interest of the students is up, so the improvement of the scores is a matter of course.
There is an old saying in China that "giving people a fish is not as good as giving people a fish." I personally think that a truly excellent teacher is passed on to students' methods, interests, problem-solving attitudes and penetrating powers. It is your skill to let students feel that this course is simple to learn. This should be the most energetic aspect of our teachers in teaching and research. It is really to stand on the students' position and think about them, and this can improve the quality of teaching.

Part 2: Reflection on the teaching of chemical balance

The knowledge of chemical equilibrium can be said to be the most difficult point of knowledge in high school chemistry. Because the content is abstract, students are not easy to understand. Therefore, the content of this section is often confused by the teacher, and the students are confused. Considering that the foundation of the students is relatively weak, I have tried to simplify the content of this lesson in the processing of the textbooks, so that the students can understand and enhance the students' interest and self-confidence.
In the processing of textbooks, I will divide this lesson into the introduction - the analysis of the example - drawing - the establishment of the concept of balance - the consolidation of the balance of the state of the five parts. A chemical equilibrium is proposed in the industrial production when considering the reaction rate and the conversion rate of the raw materials. It is also pointed out that chemical equilibrium is an important feature of reversible reaction. The reversible reaction of N2+3H2=2NH3 is used to discuss the changes of product and reactant concentration and the rate of chemical reaction before the reaction starts, during the reaction, after a period of reaction, and Drawing according to this change, it is understood that the concentration of each component remains unchanged after the reaction is carried out for a period of time, and the positive reaction rate and the reverse reaction rate are equal. This leads to the concept of chemical equilibrium state, and summarizes the chemical equilibrium state by using the words "reverse, equal, dynamic, fixed, and variable". Finally, through two sets of exercises, the judgment of the chemical equilibrium state in the type problem is summarized. symbols of. Now reflect on the teaching process of this lesson as follows:
1. This lesson is an important part of chemistry theory, and the abstraction is difficult to understand. Therefore, I use direct introduction, taking into account the actual consideration of industrial production and the conversion rate of raw materials, and propose the degree of chemical reaction research - chemical equilibrium. However, because the relationship with the students is not very close, the state of the students entering is somewhat confused. Under the class, I re-conceived this kind of introduction. Starting from the reversible reaction that students have learned, the characteristics of the reversible reaction are proposed: under the same conditions, the reaction can be carried out in both the positive reaction direction and the reverse reaction direction. In other words, it is impossible to carry out such a reaction to it. When it reacts to the maximum extent, what is it? This leads to a chemical balance.
2, the chemical balance is based on the reversible reaction, but this lesson is not very detailed for the reversible reaction, not introduced. If this is what I said to my first article, I will do both.
3. The difficulty of setting the problem should be appropriate, otherwise the student's thinking cannot be started. After the hardship, the students still do not have the knowledge and skills to answer the questions and the way of thinking. They can't find a breakthrough in solving the problem. The thinking process is difficult to start. There will be a cold field in the classroom, and students will not get a successful experience. Thinking or thinking a little can complete the problem, and the students can't experience the fun of exploration. Due to the last question, the problem is too difficult to design, and the students are somewhat confused.
4. In the classroom, we should evaluate the students' learning behavior in a timely manner. I think that I have done a good job in this class. Ask the students to answer, a "please" can close the distance between teachers and students. After each student answers the question, I will insert a sentence in a timely manner, "very good answer", "doing well", believe this Students can be motivated.
5. The exercises in the course that use several reaction characteristics to judge the chemical equilibrium state are not very good. On the one hand, from the question to the solution, I am talking about it. The students are just following me and not forming a coherent thinking. On the other hand, the students are not responding well, and the understanding is difficult, especially for the density and average relative molecules. The quality does not change and the chemical balance is not very easy to understand. First, I used to do a lot of exercises when preparing lessons, and I would like to summarize the difficult and easy to understand questions. Let me explain the lessons and let the students go on for practice. Now I feel that there are two drawbacks to this. One is that the classroom tasks are aggravated, leading to neglect of students' thinking in order to keep up with the progress. On the other hand, the student's enthusiasm for learning is not as strong as if he had made a miss after listening. Second, the difficulty in judging the equilibrium state is: the positive reaction rate is equal to the reverse reaction rate, which means that the consumption rate of the same substance is equal to the generation rate; for the reaction involving gas, it is not judged whether the gas volume and the amount of the substance change before and after the reaction. . For this section, you should pay attention to the students' thinking during class, and let the students practice to find out the difficult places to understand after class.

Part 3: Reflection on the teaching of chemical balance

This section of the factors affecting the movement of chemical equilibrium is also a combination of abstract theoretical knowledge and experimental exploration, given the teaching experience of factors affecting the rate of chemical reactions.
First, in the teaching method, the same method is adopted to ask questions----exploration-----analyze the reasons-----to draw conclusions, guide students to conduct inquiry-based learning, and make full use of communication, questioning, etc. In order to understand and consolidate knowledge, combined with image teaching, students are allowed to convert abstract theories into images. Strengthen the ability to apply laws and theories to solve practical problems.
Second, in the processing of content.
1. In view of the lack of teaching on the factors affecting the rate of chemical reaction, such as overestimating the students' experimental ability and theoretical analysis ability, in this section of content processing, first use an experiment as a case analysis guide, let go The students explored it alone, and the effect was much better than the last time.
2. Students are easily confused by the two knowledge points of the factors affecting the movement of chemical equilibrium and the factors affecting the rate of chemical reaction. In these two knowledge points, there are both connection and independence. In teaching and processing, it is necessary to separate and organically combine. For example, if the temperature is raised, the equilibrium moves toward the endothermic reaction, and the rate will increase, but the student will misunderstand that the rate of the exothermic reaction direction decreases.
III. Inadequacies: 1. Due to the lack of proficiency in student experiments, the time is still not enough. Some of the inquiry activities have not been fully carried out, and the time for self-study is still insufficient. 2. The cultivation of students' experimental inquiry ability will be strengthened in the future.

Part 4: Reflection on the teaching of chemical balance

First, strive to do the classroom intensive and intensive, refined and literally can be said to be cliché, but in the teaching practice it is an eternal theme. It needs constant innovation, constantly filling in new teaching concepts, teaching thinking and teaching inquiry, and striving to achieve the intensive and refined teaching of each class. It is a classroom teaching goal that teachers must pursue at all times.
In the course of preparing for the lesson, I first carried out the rough framework and the large scan of the main clues on the large structure of the chapter knowledge. After setting the general direction, we focused on the organic connection between the knowledge points and the rational laying of the knowledge gradient. The difficult and difficult knowledge should be introduced naturally and rationally. Efforts will be made to achieve breakthroughs in the classroom and after-school self-study, so that students can easily appreciate the charm of logic and essence in the deduction of chemical theory and analysis in the face of apparent abstract, scattered and flexible chemical theory knowledge. Realize the teaching goal of classroom teaching to cultivate students' scientific thinking methods. The class examples and after-school exercises are carefully selected according to the type of questions, so that students can be targeted in the practice, with less effort and solidity.
Regarding the processing of textbooks, I think we should pay attention to the following questions:
1. The teaching of the influence of external conditions on the rate of chemical reaction should firstly clarify the relationship between internal and external factors. On this basis, the key to the influence of external factors on the chemical reaction rate is to highlight the change of reaction conditions, the fundamental change of chemical reaction rate - effective Collision theory. The theory of collision and activation molecules is still the core essence of the teaching of this section.
2. The influence of pressure on the rate is more complicated. The key is to distinguish the cause of the pressure change. However, in the ever-changing problem of pressure on the rate, we must always guide students to grasp a basic invariable principle: the influence of pressure. Ultimately, the effect of concentration on rate. Changes in pressure have no effect on the rate if they do not cause a change in concentration.
3. The introduction of the concept of chemical equilibrium is based on a review of the dissolved crystallization balance that is already familiar to the classmates. It is analogous to chemical equilibrium and finds the characteristics of the chemical equilibrium state—moving, etc., inverse, fixed, and changing. Avoid some students will understand the "concentration unchanged" when the balance is reached, "the concentration is equal", the sample data of the CO, H2O, CO2, H2 concentration after the reaction on the textbook can be slightly modified to avoid misleading.
4, the detection of chemical equilibrium part of knowledge is mainly reflected in three aspects: the determination of the equilibrium state, the calculation of the chemical balance, the determination of the equivalent balance. These three aspects are all difficult points. When dealing with such knowledge, teachers should firmly grasp the principle of solving problems: never change. 1 The criterion for the balance state is summarized in various data, but in the final analysis, it is to see whether the rate of positive and negative is equal or whether the concentration is constant. 2 The key to balance calculation lies in the specification of the relationship between the starting amount, the amount of change and the amount of balance. Applying, 3 equivalent balance judgment can be programmed to guide students to first develop a perceptual understanding of the concept through self-practice, and then the teacher summarizes the judgment basis: constant temperature and constant capacitance to see the value, volume does not change the proportion; constant temperature and constant pressure to see the ratio.
Second, the abstract knowledge is vivid and visualized to embody more of the micro-abstracting theories in this chapter. In the preparation and teaching process, we should make full use of experiments, drawings and vivid images, close to the reality of life, and easy to understand and reflect the characteristics of the times. Students like to hear examples of metaphors to help students understand abstract knowledge, resolve difficulties, and make students realize that many of the knowledge of natural sciences and social sciences are the same, improve students' awareness and cultivate students' image thinking.
The textbook content of this chapter has exemplified a large number of image metaphors. Now I have listed some examples of the references I have cited in teaching:
1. The use of a positive catalyst reduces the activation energy and the percentage of activated molecules increases.
Example of metaphor: High jump in physical education class, lowering the height of the squat, and skipping more students.
2. There are many ways to establish balance. Proverb: All roads lead to Rome.
3. The reaction between iron and sulfuric acid is slowed down by the addition of sodium acetate and the amount of hydrogen produced is unchanged. Here, the role of acetate can be compared to a bank. The ionized hydrogen ion of sulfuric acid is a large amount of cash in the family. Some of it is deposited in the bank. When it is needed, it is used to reduce the rate of money, but the total amount of funds has not changed.
I personally have a point of view: a truly good teacher is passed on to students' methods, interests, attitudes that are not surprising when solving problems, and the penetrating power of examining problems. I heard a lot of online continuing education from Xiaozhuang College a few days ago. Among them, Professor Qian Zhiliang has a very deep memory. When he talked about the difference between teachers and experts, he said that the teacher is complicated. Incomprehensible problems or things are presented to students in their own language, in the simplest and easy-to-understand language. This is the teacher. It is your skill to let students feel that this course is simple to learn. This should be the most energetic aspect of our teachers in teaching and research, and it is really to stand on the students' position for their sake. To improve the quality of teaching, we must start with our business skills, rather than disguised in the students.

Part V: Reflection on Chemical Balance Teaching

As part of the principle teaching, it is formed from general to special, from concrete to abstract, from phenomenon to essence. Teachers should pay attention to cultivating students in the process of teaching. The ability to interpret logical reasoning.
As far as my own class is concerned, since students have mastered the concept and meaning of equilibrium constants, my design idea is to let students know the influence of temperature on chemical balance through perceptual knowledge, and guide students to analyze temperature from the perspective of equilibrium constant. Why can it affect the chemical balance, sum up the effect of temperature on the balance; then let the students rationally analyze the effect of the predicted concentration on the chemical balance----based on the provided reagent design experiments, propose an experimental plan----- discuss the evaluation experiment plan ------Implementation of experimental programs ------Get information-----Verify predictions so that students can experience the complete inquiry learning process and improve students' scientific learning methods and abilities. Finally, the teacher in this lesson gives students the opportunity to move the chemical equilibrium caused by the change of external conditions. The new equilibrium state is the change of the equilibrium constant, and the other is the constant of the equilibrium constant, so that some students will study some topics in the future. The basis for the equivalent balance mentioned in the paper. Finally, students can solve problems by students to further improve students' understanding.
In the implementation process of this lesson, the cultivation of knowledge and skills is accomplished through teacher-led and self-directed learning. This lesson focuses on the process and methods, enabling students to predict, design experiments, implement experimental programs, and gain sensibility. Cognition, combined with rational analysis, deepens the understanding of new knowledge, and also enhances students' ability to explore scientific experiments.
At the end of the lesson, through reasonable design exercises, both consolidate knowledge and educate students on emotional attitudes and values, let students know that using the knowledge of chemistry can solve many problems in production and life, and experience the value of learning chemistry.