Knowledge points of chemistry and life in college entrance examination

A fish jumped into a dragon, and Dapeng spread its wings, which was earth-shattering. Being good at sorting out the knowledge of chemistry will help your college entrance examination go smoothly. The following are my knowledge points for chemistry and life in the college entrance examination for your reference!

Knowledge points of chemistry in college entrance examination

1. The larger the atomic radius of alkali metal elements, the higher the melting point, and the greater the activity of simple substances.

Wrong, the melting point decreases with the increase of atomic radius.

2. Both sulfur and white phosphorus are soluble in organic solvents such as carbon disulfide and carbon tetrachloride, while organic acids are insoluble in water.

Wrong, lower organic acids are easily soluble in water.

3. Add enough concentrated sulfuric acid into the saturated solution of copper sulfate to generate blue solid.

Correct. After concentrated sulfuric acid absorbs water, sulfuric acid precipitates.

4. Only active metals or nonmetallic elements can react with cold water and release gaseous elements.

Error, such as 2na2o2+2h2o = O2 = 4 NaOH.

5. Liquefy the air, then gradually raise the temperature, prepare oxygen first, and leave nitrogen.

Wrong, the boiling point of N2 is lower than O2, so N2 will be obtained first and liquid oxygen will be left.

6. The main problem to be solved in smelting pig iron into carbon steel is to remove all elements except iron from pig iron and purify it.

The mistake is to reduce the percentage content of C in pig iron instead of purification.

7. Although all potassium-containing substances in nature are easily soluble in water, the K% in soil is not high, so it is necessary to apply potassium fertilizer to meet the needs of plant growth.

Wrong, the content of potassium in nature is not low, but exists in the form of complex silicate, which is insoluble in water.

8. When preparing bleaching powder, preparing Bordeaux mixture and improving acid soil, hydrated lime should be used.

Correct. Bleaching powder is made by the reaction of hydrated lime and Cl2, and Bordeaux solution is a mixture of hydrated lime and copper sulfate.

9. Silicon dioxide is an acidic oxide, which is insoluble in acidic solutions.

Wrong, silicon dioxide can be dissolved in hydrofluoric acid.

10. Iron filings dissolved in excess hydrochloric acid, and then added with chlorine water or bromine water or iodine water or zinc nitrate, will produce Fe3+.

Wrong, FeI2 can be obtained by adding iodine water, because Fe3+ is not as oxidizing as Cl2 and Br2, but stronger than I2. There is no FeI3 in the solution, and 3mol electrons are transferred.

1 1. at room temperature, concentrated nitric acid can be stored in aluminum cans, indicating that aluminum does not react with concentrated nitric acid.

Wrong. Passivation is a chemical property, which is essentially to form a dense Al2O3 oxide film to protect aluminum cans.

12. When CO2 enters saturated solution, such as NAALO2, Na2SiO3, Na2CO3, Ca(ClO)2, NaOH, C 17H35COONa, C6H5ONa, etc., white precipitate will appear. And when excessive CO2 is continuously introduced, the white precipitate still does not disappear.

Error: CO2 was continuously injected into Ca(ClO)2 until it was excessive, and the white precipitate disappeared, and finally Ca(HCO3)2 was obtained.

13. A large amount of sulfur dioxide in the atmosphere comes from the combustion of coal and oil and the smelting of metal ores.

correct

14. A clear solution consists of NH4Cl, AgNO3 and NaOH. If enough nitric acid is added, white precipitate will be produced.

Correct, NH4Cl, AgNO3 and NaOH react to form [Ag(NH3)2]+ AgCl and NH4NO3 are formed after adding enough nitric acid.

15. In order to make full use of raw materials, the tail gas of sulfuric acid industry must be purified and recovered.

The mistake lies in preventing air pollution.

16. React with enough 1mol NaOH solution.

correct

17. Sodium sulfide can neither react with caustic soda solution nor with bisulfate?

Wrong, sodium sulfide can react with bisulfate:? Na2S+H2S====2NaHS？

18.SCN-, I-, AlO2-, S2-, CO32-, HCO3- etc. can't be stored in large quantities in a solution containing high concentration of Fe3+?

Correct. Fe3+ can coordinate with SCN-, undergo redox reaction with I- and S2-, and undergo double hydrolysis reaction with CO32-, HCO3- and AlO2-.

19. activated carbon, sulfur dioxide, chlorine water, etc. Can make magenta fade, but the reaction properties are different?

Correct, the adsorption of fuchsin by activated carbon is a physical change, SO2 is an unstable compound and reversible, and chlorine water is a redox reaction and irreversible?

20. Ethyl acetate, tribromophenol, sodium acetate, liquid bromine, glass, barite and heavy calcium can all react with caustic soda?

Error, barite (main component BaSO4) does not react with caustic soda?

2 1. FeBr3, FeCl2 and Br2 can be obtained by introducing a certain amount of Cl2 into FeBr2 solution.

Error, Fe2+ and Br2 do not exist * * *?

22. Because Fe3+ and S2- can undergo redox reaction, Fe2S3 does not exist?

Wrong. Fe2S3 can be obtained by adding Na2S into Fe3+ solution with a PH=4 of about 4, and the solubility product is extremely small.

23. Sodium sulfite and hypochlorous acid can be obtained by introducing a small amount of sulfur dioxide into sodium hypochlorite solution?

Wrong, hypochlorous acid can oxidize sodium sulfite to get NaCl and H2SO4?

24.5.6g of iron reacts with enough acid to transfer 0.2NA number of electrons?

Wrong, if it reacts with strong oxidizing acids such as nitric acid to transfer 0.3NA?

25. The compound containing the highest valence element does not necessarily have strong oxidation?

Correct, such as dilute HClO4, H2SO4, etc?

26. The weaker the reducibility of a simple substance, the stronger the oxidizability of its cation?

Errors, such as Cu's reducibility is weaker than Fe's, and Cu2+' s oxidation is weaker than Fe3+'s?

27. CuCO3 can be prepared by adding CO32- into Cu2+ solution?

Wrong, it is impossible to prepare pure CuCo3. Adding CO32 to Cu2+ solution will immediately produce Cu2(OH)2CO3.

28. Element X can replace element Y in salt solution, so the physical properties of elements X and Y can be: (1) metal and metal; (2) nonmetals and nonmetals; (3) metal and nonmetal; (4) nonmetals and metals; ?

Wrong, (4) nonmetals and metals can't have this reaction.

29.H2S, HI, FeCl2 _ 2, concentrated H2SO4, Na2SO3, phenol and other solutions are deteriorated by long-term redox reaction in air.

Error: H2SO4 deteriorates due to water absorption and SO3 release.

30. Concentrated nitric acid and concentrated sulfuric acid can react with copper and iron at room temperature.

Error, concentrated sulfuric acid does not react with copper at room temperature.

Interesting memory method of high school chemistry knowledge

First, the memory method of songs and rhymes.

The memory method of children's songs and rhymes is to use phonology to compile the chemical knowledge that needs to be memorized, which is informative and interesting, catchy and easy to remember and memorize. For example, the operation song of pouring the liquid in the narrow-mouth bottle into the test tube: "Hold the label with three fingers of the palm, and the two mouths fall relative to the line of sight." "Three-finger grip" refers to holding the test tube tightly with thumb, forefinger and middle finger; "Eye drops" refers to observing the amount of liquid in the test tube when pouring liquid to prevent excessive dumping. For another example, nitric acid can be prepared by the following ammonia oxidation: "heating catalyzes ammonia oxidation, and ammonia-nitrogen water is heated;" Nitric oxide reoxidizes, and nitrogen dioxide is brown; Nitrogen dioxide is dissolved in water and will come out to make nitric acid. "

Symbols, valences, solubility tables and other elements can be memorized by composing music. In the process of teaching and learning, rhyming can really be used to help you remember, so that you can consolidate your learning results easily and happily.

Second, homophonic memory method

Homophonic memory method is to combine the chemical content that needs to be remembered with the homonym in daily life for memory. For example, the top three elements in the earth's crust are "oxygen, silicon and aluminum", which can be homonymized as "raising a daughter". For another example, the order of metal activity is: potassium, calcium, sodium, magnesium, aluminum, manganese, zinc and iron; Tin, lead, copper, mercury, silver, platinum and gold can be homophonic: "Add 100 Jin of that beautiful new tin and lead."

Third, the method of knowing memory.

The way to know and remember is to understand and reprocess some abstract concepts and then memorize them skillfully. For example, the experimental operation of reducing copper oxide by hydrogen or carbon monoxide is: at the beginning of the experiment, ventilation is first followed by heating, and at the end of the experiment, heating and ventilation are first stopped, so it can be recorded as "gas comes out early and returns late, and alcohol lamp comes out early." For another example, the four basic reaction types are respectively understood as "one divides into two" (decomposition reaction), "combination reaction", "substitution reaction" and "mutual exchange" (double decomposition reaction).

Image metaphor memory method is to visualize those concepts that are difficult to remember, and remember them with intuitive images with vivid metaphors. For example, the arrangement law of electrons outside the nucleus is: "Low-energy electrons usually have more opportunities near the nucleus, while high-energy electrons usually have more opportunities far away from the nucleus." This question is abstract, and I can't understand it at once.

Fourthly, associative memory method.

Associative memory method is to remember some chemical experiments or concepts by associative method. Association method is a confirmatory memory method, which is the product of the connection between old and new knowledge. In the process of chemistry teaching, we should grasp the characteristics of the problem and expand the association accordingly. For example, the experimental process of reducing copper oxide by hydrogen, carbon and carbon monoxide can be remembered through experimental association and comparative association. For example, put the concepts of simple substance and compound together and remember: "Pure substances composed of the same (different) elements are called simple substances (compounds).

For small problems with few words and confusing words, we should grasp the key words and make strange associations. For example, the purpose of sodium hydroxide is to be used in soap, petroleum, papermaking, textile, printing and dyeing industries, which can be recorded as: "Paper (fabric) is dyed with fatty oil".

Five, centralized memory method

Centralized memory method is to remember a chemical knowledge or law by selecting representative words or words and shrinking them into a skeleton on the basis of profound understanding. For example, the seven experimental steps of making oxygen in the laboratory are recorded as: "check, install, clamp, point, close, move and extinguish." "Inspection" means to check whether the device leaks air; "Loading" means loading drugs into test tubes; "Clamping" refers to clamping a test tube on an iron frame; "Point" means to light the alcohol lamp; "Receiving" means collecting gas; "Move" means to move the catheter out of the water first; "Extinguish" means to extinguish the alcohol lamp. Another example is that the attention points in the filtration operation are condensed into: "one paste, two low, three rely on".

Six, guessing memory method

The guessing memory method is to compile some chemical knowledge into informative, interesting, vivid and humorous riddles for memory. For example, the riddle of remembering the nature of carbon monoxide is: "The moon on the left is curved and the moon on the right is round. The crescent moon can keep warm, and the full moon can help fuel. Toxic and colorless, flammable after reduction. "

Seven, image metaphor memory method

If we make such an analogy, we can easily understand and remember it. Compare the earth to the nucleus, birds with high abilities such as geese and eagles to electrons with high energy, and birds with low abilities such as sparrows and swallows to electrons with low energy. Birds with high ability tend to fly in the sky higher than the ground, while birds with low ability tend to be very low from the ground. Another example is that there are double bonds in organic chemical olefins, which are prone to addition and polymerization. When ethylene polymerizes, polyethylene is produced. We can vividly use the analogy of "C=C" and "-C-C-" holding hands, which makes it easier to remember wishes. In short, there are many ways to remember interesting memories, such as graphic memory, inductive memory, lyrics memory and so on.

In the process of teaching and learning, we can sum up our own memory methods according to the actual situation. Just remember it quickly.

Accurate and firm memory is a good memory method.

Summary of error-prone knowledge points in senior high school chemistry

1, polybasic oxyacid, specifically polybasic acid, depends on the number of H in the acid.

How many H+ s a polybasic acid can ionize depends on how many hydroxyl groups there are in its structure, and non-hydroxyl hydrogen cannot be ionized. For example, phosphorous acid (H3PO3) seems to have three H's, which are similar to ternary acids, but in its structure, one H and one O are directly connected to the central atom, and do not constitute hydroxyl groups. There are only two o's and h's that make up hydroxyl groups. So H3PO3 is a dibasic acid. Of course, some factors have to be considered, such as Lewis acid H3BO3, which cannot be explained.

2. The acidic salt solution is acidic.

On the surface, the "acid" salt solution is of course acidic, but it is not. What kind of acid salt it is, it should be discussed according to the situation. If this is the acid salt of a strong acid, because it ionizes a large amount of H+ and the anion does not hydrolyze, then the acid salt solution of the strong acid must be acidic. However, the acid salt of weak acid should be compared with its ability to ionize H+ and the degree of anionic hydrolysis. If the degree of anion hydrolysis is large (such as NaHCO3), the solution is alkaline; On the contrary, if the anion has a strong ability to ionize H+ (such as NaH2PO4), the solution is acidic.

3.H2SO4 has strong oxidation.

That's not right. Just put the word "thick" in front of it. Concentrated H2SO4 exists in molecular form, and its oxidation is reflected in the whole molecule. S+6 in H2SO4 is easy to get electrons, so it has strong oxidation. However, dilute H2SO4 (or SO42-) has almost no oxidation (even H2S cannot be oxidized), which is much weaker than H2SO4 (or SO32-). This also shows that the oxidation of low-priced nonmetal oxyacid radical is stronger than that of high-priced nonmetal, which is the same as that of HClO and HClO4. Therefore, when H2SO4 is strongly oxidizing, it must be rigorous, and the word "concentration" should be added in front.

4. When writing ionic equation, the reaction between products is not considered.

Considering the speed of solving problems, when judging whether ionic equation's writing is right or wrong, you can "read it four times": see if the product is correct; Second, see if the charge is conserved; Third, see if the split is reasonable; Fourth, see if it meets the conditions of topic restriction. Considering from the depth of problem-solving thinking, the composition of the product is comprehensively judged by using chemical principles such as contact redox reaction and double decomposition reaction. Typical reaction in middle school: low-valent iron compounds (oxides, hydroxides, salts) react with nitric acid; Simple iron reacts with nitric acid; +3 Reaction of iron compounds with reducing acids such as hydrogen iodide solution.

5. When separating the mixture, ignore the restriction of reaction order.

The separation and purification of the mixture put forward specific requirements for the principle of chemical reaction: the reaction should be fast, the impurities should be removed by adding excessive reagents, and the selected reagents should be easy to remove without introducing new impurities.

6. Ignore the crystal structure when calculating the reaction heat.

When calculating the reaction heat, it is easy to ignore the crystal structure. In middle school, the atomic crystals of valence bonds are often calculated: 1 mole of diamond contains 2 moles of carbon-carbon bonds, and 1 mole of silicon dioxide contains 4 moles of silicon-oxygen bonds. Molecular crystal: 1 mole contains valence bonds, for example, 1 mole ethane contains 6 moles of carbon-hydrogen bonds and 1 mole of carbon-carbon bonds.

7. The law of solubility of uncertain substances.

The change law of solubility of substances can be divided into three categories: first, the solubility increases with the increase of temperature, such as potassium chloride and potassium nitrate; Second, the solubility increases with the increase of temperature, but the degree of increase is small, such as sodium chloride; The third kind, the solubility decreases with the increase of temperature, such as gas, sodium hydroxide, etc. Some students can't understand the relationship between gas solubility and temperature.

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