How should I do chemistry reasoning questions in junior high school?

Specific topics need to be analysed.

1.Reading questions: The main task of reading questions is to first dismantle and modify the general idea of the question, find key words and sentences, and obtain surface information. Don't rush to answer questions when you see a little familiar background information, and jump to conclusions, which can easily fall into the trap set by the college entrance examination questions.

2.Examination of the question: Refine and process the information obtained from reading the question, look for obvious or potential breakthroughs, and pay more attention to digging out the hidden information "questions".

The title "is often some special structure, state, color, special reaction, reaction phenomenon, reaction condition and use, etc. The most important thing in reviewing the problem is to find out the "topic".

3.Problem solving: After finding the "problem", it is time to choose the appropriate solution method.

The commonly used methods for solving inorganic inference problems are: forward extrapolation, reverse inference, comprehensive reasoning, hypothesis, calculation, experiment, etc. The usual mode of thinking is to make bold conjectures based on information, and then verify the conjecture through temptation; When the test is blocked, re-broaden the thinking, make new hypotheses, and verify them.

Generally speaking, it is indispensable to consider the knowledge of common regularity first, and then the knowledge of uncommon particularity.

4.Validation: Regardless of the method used to introduce conclusions, the substances introduced should be substituted for validation.

If it is in perfect agreement with the title, then our conclusion is correct. Finally, when you get the correct conclusion, you should also pay attention to the standard writing according to the requirements of the topic, such as the name is required to be written, do not write the chemical formula.

Chemistry inference questions are the compulsory question type of chemistry in the high school entrance examination, and they are also the most difficult question type that candidates generally feel. The junior high school chemistry inference question is a more comprehensive question type, and a good foundation is required to do this type. That is to say, the foundation is strong, and all knowledge points are mastered, and the inference questions can be made well.

The special properties of chemical substances are the most important topics in the inference question. Special chemical properties such as toxicity, corrosiveness, flammability, etc.; Special physical properties include color, water absorption, melting point, boiling point, etc. Inferring substances from the properties of these particular substances is nothing more than an important way.

The skills and methods of junior high school chemistry inference questions are as follows:

1.Review: Review the problem and re-ask the problem Quickly go through the block diagram, try to represent it in the block diagram, and clarify the solution requirements. Hu Wang.

2.Find: Find the "problem", that is, find the breakthrough to solve the problem, this step is very crucial.

3.Analysis: Starting from the topic, connecting new information and old knowledge learned, making bold guesses, following the vine, applying mindfulness to do late reverse thinking, divergent and convergent thinking, horizontal and vertical thinking, etc., conducting comprehensive analysis and reasoning, and drawing preliminary conclusions.

4.Verification: Verify that it is correct, put the result into the original question for testing, and it is considered correct if it is completely conformed.

5.Answer: Write the answer according to the requirements of the question.

The color of common substances in junior high school chemistry.

a) The color of the solid.

1. Red solid: copper, iron oxide.

2. Green solid: basic copper carbonate.

3. Blue solid: copper hydroxide, copper sulfate crystals.

4. Purple-black solid: potassium permanganate.

5. Light yellow solid: sulfur.

6. Colorless solids: ice, dry ice, diamond.

7. Silver-white solid: silver, iron, magnesium, aluminum, mercury and other metals.

8. Black solid: iron powder, charcoal, copper oxide, manganese dioxide, ferric tetroxide, (carbon black, activated carbon).

9. Reddish-brown solid: iron hydroxide.

10. White solid: sodium chloride, sodium carbonate, sodium hydroxide, calcium hydroxide, calcium carbonate, calcium oxide, copper sulfate, phosphorus pentoxide, magnesium oxide.

While reading the problem, use a pencil to draw out the special conditions, such as precipitation, gas, water and other metathesis reaction conditions, as well as the color and state of the product reactants. The color of the material that can be used in junior high school is like copper, bright red; reddish-brown rust; precipitation of blue flocculent copper; green ferric ions; Yellow ferric ions; Blue divalent copper ions. Wait a minute.

It's easier to figure this out.

In junior high school, there are not many coefficients that involve inferring that there is a substance in the body, but once they appear, special attention is needed, because most of these conditions are restrictive, and many group solutions may be introduced, and only those that conform to the coefficient relationship are the correct answers. Therefore, it is easy to ignore the condition of coefficient relationship and make mistakes.

The inference question tests knowledge and mentality. You must not panic, even if you can't push it out, you can't panic, calm down, push it slowly, it will always be pushed out. And the high school entrance examination will not be difficult, do more questions, and you will be able to master the trick.

First of all, there will be some characteristic clues in the question! For example, gases, precipitation, color state changes, etc., at this time, you need to go through the relevant equations in your mind according to these characteristics!

Secondly, it will give some amount of relationship! At this time, you can call it up according to your usual memory of the amount of the equation!

Again, maybe the equation you call up is not necessarily the answer to this question, at this time you need to use the precipitation and color it provides as the leading clue to get the key clue! Think again! It's definitely not out of your usual equation memory range!

Finally, you must be calm and don't be in a hurry, which many people can't do!

Good luck!

1.Anything that is too absolute is often wrong, for example, substances that contain carbon are organic matter.

2.The reaction conditions are important, for example, the products of iron combustion in air and pure oxygen are very different.

3.For example, cellulose, starch, glucose, and protein are all polymer organic compounds, so the exceptions to this substance should be distinguished carefully.

There are no skills, skills are just enough structured knowledge that you learn, plus problem review, reasoning. Generally speaking, similar substances have similar properties, so it is important to grasp the classification of substances. There is also the concept of matter to be distinguished into.

Therefore, it is important to classify knowledge concepts in the process of knowledge learning.

The equations for common metal reactions and acid-base salt reactions must be remembered, and the phenomena of chemical reactions, products, colors, gases, and precipitations must be remembered. The usefulness of the experimental apparatus needs to be familiar with the understanding, impurities, mixtures, unknown substances, and step-by-step analysis is good.

Based on the personal experience of the following friends, it is as follows.

1.Examine the problem and look for a breakthrough, especially some very special properties. For example, carbon dioxide and clarified lime water have a precipitation reaction, and in junior high school, as soon as you see a gas with this reaction, it must be carbon dioxide.

2.Remember the properties of some substances, not too much, but keep in mind that there are such phenomena in junior high school, and grasp the key phenomena.

3.Familiarize yourself with chemical equations, which is very important, and then find the rules to memorize, end.

4.If you can't push it out, continue to look at the problem and look for hidden conditions, such as hydrogen ions in an acidic solution (pH<7).

5.Memorize equations and be able to combine them with phenomena.

The inference questions are mainly about chemical equations and the properties of matter! First of all, you should be proficient in the types and equations of metathesis reactions in junior high school! Then use the ** method to list the phenomenon of two pairs! From the special phenomenon as a breakthrough, you can solve the problem one by one!

Carefully review the question and pay attention to the implicit conditions given in the question conditions

For junior high school chemistry, in fact, there is not a lot of content, it is necessary to understand the properties of the substances learned, to know some important reaction phenomena, and then to know how to transfer. In the process of doing the question, you must first see the question clearly and make inferences step by step according to the prompts in the question. There are generally several situations:

1. Hints of experimental phenomena. For example, in the question, it is said that such and such a substance reacts with such and such a substance to produce a substance with a certain color or a certain property. For example, if a certain gas can be generated to clarify lime water and become turbid, you can infer that this substance is carbon dioxide, and then associate the formation of carbon dioxide, which is the chemical equation for lime water to become turbid, and so on.

Second, the physical properties of the substance prompt, directly tell you some of the physical properties of a certain substance, such as color, smell, etc., generally these substances are common substances.

3. Generator hints, which will tell us certain properties of the final product, and this kind of question generally uses the reverse deduction method.

In short, the only way is to grasp the properties of the substances you are learning and the reaction equations and reaction phenomena related to them, and pay attention to the details in the process of doing the problem, such as the gas precipitation symbol in the equation, whether the name of the substance or the chemical formula or the common name is required to be written.

The high school entrance examination is coming, don't worry, break through each according to your weaknesses, draw inferences from one another, and believe that you can get good results!

To do inference questions, you must be familiar with the various equations required by junior high school, and remember that there are obvious phenomena, such as precipitation, gas, etc. There are also properties of substances, such as color, smell, state, etc. Generally, the high school entrance examination will not test the cold equations.

It's easy to remember the nature of special substances and find a breakthrough.