Chemistry Deduction Question Skills, How to Do Chemistry Deduction Questions What are the skills

It is inferred from known conditions, such as precipitation, color, and gas, as well as some common reaction conditions, special phenomena in the reaction process, etc

The known conditions in the question, look at the color of the precipitation, the smell and color of the gas released, and make bold guesses.

I have uploaded the common use and skills of chemical inference questions, please check them in time!

Here are some tips for chemistry inference questions:

1. Take the characteristic color of the substance as the breakthrough point. Black substances: copper oxide, carbon, ferric oxide, manganese dioxide, iron powder in the order of thinking and selection; Red elemental:

copper or red phosphorus; Green substance: basic copper carbonate (patina); reddish-brown (or brownish-red lead) material rust (or iron oxide);

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2. Take the use of materials as a breakthrough. The use of matter is the focus of chemistry learning, because the purpose of learning knowledge is ultimately to apply knowledge to solve practical problems. The new curriculum concept places special emphasis on the application of knowledge. Students' abilities are tested in the application of knowledge.

3. Take the characteristic composition of matter as a breakthrough. The characteristic composition of matter is prominent in the characteristics of the elements, such as: organic matter must contain carbon elements; Acids must contain hydrogen, not necessarily oxygen; The alkali must contain hydrogen and oxygen elements, not necessarily metal elements; Gases with the same elemental composition are CO2 and CO; Liquids with the same elemental composition are H2O2 and H2O;

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4. Take the typical reaction conditions as the breakthrough point. Since there are not many chemical reactions involved in junior high school chemistry, some chemical reaction conditions have obvious directions in the questions.

5. Take the typical properties of matter as a breakthrough. The properties referred to here should have distinct personalities, such as: water absorption, dehydration, dissolution in water and exothermic of concentrated sulfuric acid; Solid sodium hydroxide dissolves in water with an increase in temperature and it can absorb water deliquescent; quicklime reacts with water to release heat; Ammonium nitrate dissolves in water and the temperature drops;

6. Take the special phenomenon of chemical reaction as a breakthrough. Special reaction phenomena are often used as a breakthrough to infer the question, for example: ammonia can make the wet red litmus test paper blue; Sulfur burns in the air and gives a pale blue flame, while when it burns in oxygen, it emits a blue-purple flame;

7. The most common elements or substances with the most breakthrough of elements or substances are as follows. The most abundant element in the earth's crust is O, and the most abundant metallic element is Al; The element that forms the most compounds is C; The element with the least number of protons is h; The gas with the smallest relative molecular mass and the smallest density is H2;

8. Take the common name of matter as a breakthrough. Common names commonly used in inference questions: marble, limestone (main component: calcium carbonate CaCO3); table salt (main ingredient: sodium chloride NaCl);

Chemistry inference questions account for a large part of the chemistry exam, and I have compiled some ways to do chemistry inference questions.

Due to the lack of operational knowledge and strategic knowledge to solve inference questions, students always have a feeling of being confused and unable to start in the process of analyzing and solving element inference questions, so the answers are often blind, arbitrary, and lack of rigor and integrity.

In fact, in the process of solving some element inference problems with complex backgrounds, we can get more than one possible guess through the preliminary analysis of the background of the problem, then we can use the argumentation method to put the hypothesis that can be cautious and frank into the original question, and compare it with the logical relationship in the question, if the conclusion is consistent with the conditions of the original question, it is the correct answer, otherwise, the conclusion is wrong. You should not sift through it and answer it blindly.

1 Material characteristics.

1) Solid color: Fe, C, Cuo, Mno2, Fe3O4 (black); DuCu, Fe2O3 (red); Cu2(OH)2CO3 (green); cuso4?5H2O (blue), S (yellow).

2) Solution color: contains Cu2+ (blue); Contains Fe2+ (light green); Contains Fe3+ (yellow).

3) Common solid elements are Fe, Cu, C, S; Gas elements include H2, N2, and O2; Colorless gases include H2, N2, O2, CO, CO2, CH4, SO2; Substances that are liquid at room temperature are H2O.

2 Characteristics of the phenomenon.

1) Flame color: S burns in O2 (blue-violet); S, H2 burns in air (light blue); CO and CH4 are burned in the air (blue).

2) Precipitate color: BaSO4, AGCL, CaCO3, BACO3 (white); Cu(OH)2 (blue); Fe(OH)3 (reddish-brown).

3) The gas that can make the burning wood burn normally is air, the gas that burns more vigorously is O2, and the gas that is extinguished is CO2 or N2; The gas that can rekindle a sparkled stick is O2.

Organic inference and synthesis questions can comprehensively test the degree and application level of students' knowledge of the structure, properties, synthesis methods, and selection of reaction conditions of organic matter, and can also test students' self-learning ability, observation ability, comprehensive analysis ability, and logical thinking ability.

Organic inference is a type of question with strong comprehensiveness and large thinking capacity, and its general form is to infer matter, write terms, and judge nature.

The above is the method I have compiled to do chemical inference questions, I hope it can help you.

The chemical substance inference question requires the candidate to deduce the type, properties, and counter-judgment of the substance according to the conditions given. Here are some tips for solving such problems:

1.Determine the type of chemical reaction: The topic often involves chemical reactions, and it is first necessary to determine the type of reaction according to the reaction balance and products, such as acid-base neutralization reaction, redox reaction, etc.

2.Use chemistry knowledge to analyze the question stem: Analyze the given information and chemistry knowledge to find a breakthrough in the problem. It is necessary to understand some chemical concepts, such as valency, chemical formulas of substances, etc., and also have a certain understanding of chemical experiments.

3.Start with chemical experimental data: Experimental data can often provide some useful information, such as the specific amount of reactants, the specific amount of products, the amount of gas produced, etc., which can help to guess the type of substance and chemical equation of the reaction.

4.Itemized exclusion options: Some options may not match known criteria, and hail is instructed to exclude these options individually until it finds an option that meets the criteria.

5.Consider special circumstances: Some questions may require candidates to consider special conditions, such as reaction temperature, reactant solubility, etc., which often require extra attention.

Chemical Inference Problem Solving Skills:

1. Take the characteristic color of the substance as the breakthrough point.

Black substances: copper oxide, carbon, ferric oxide, manganese dioxide, iron powder in the order of thinking and selection;

Red elements: copper or red phosphorus; Green substance: basic copper carbonate (patina);

reddish-brown (or brownish-red) material rust (or iron oxide);

Blue solution: solution containing Cu2+ (e.g., copper sulfate, copper chloride, copper nitrate solution);

Blue substance: cholelum (blue alum cuso45h2o);

Yellow elemental: sulfur(s);

Yellow solution: solution containing Fe3+ (e.g., ferric chloride, ferric sulfate, ferric nitrate);

Light green solution: solution containing Fe2+ (e.g., ferrous chloride, ferrous sulfate, ferrous nitrate);

Fuchsia solution: potassium permanganate solution;

Blue precipitate: copper hydroxide.

Reddish-brown precipitate: iron hydroxide.

Common white precipitates: calcium carbonate, barium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, silver chloride.

2. Take the typical properties of matter as a breakthrough.

The properties referred to here should have distinct personalities, such as: water absorption, dehydration, dissolution in water and exothermic of concentrated sulfuric acid; Solid sodium hydroxide dissolves in water at an increased temperature and it can absorb water and deliquescent; quicklime reacts with water to release heat; Ammonium nitrate dissolves in water and the temperature drops; Hydrogen is the lightest gas; Water is liquid at room temperature; Oxygen can rekindle the sparkled sticks;

Anhydrous copper sulphate turns blue when exposed to water; Carbon dioxide passes through the clarified lime water and becomes turbid; The gas that can make the black Cuo turn red (or the red Fe2O3 turn black) is H2 or CO, and the solid is C; The reaction of acid-base indicators with acidic or alkaline solutions, and so on.

No matter how the question comes out, it is also out of what you should know, the basic things are mastered, the inference question is not difficult, it is very important to understand the meaning of the question, understand the meaning of the question you can know at once what he is going to test you, this is also to rely on the accumulation of some questions, not to do the question for the sake of doing the question, so that the question is not meaningful, every question can think and think, then you will learn a lot, your ability to improve quickly, the ability of the human brain is still very strong, you come on development, come on you can do it!

First of all, it is necessary to have a solid foundation and do a good job of accumulation work in ordinary times. It is enough to summarize the fragmented knowledge points frequently.

Ask the teacher and find the topic to do on your own.