MindMap Gallery Summary of key and difficult points in college entrance examination chemistry
High school chemistry is believed to be a nightmare for many high school students. The main reason is that the distribution of important and difficult knowledge is too scattered. If you cannot summarize and review it well, you will always miss one and miss the other, making it difficult to grasp the essence. I got a score of 260 in science and mathematics in the college entrance examination, and almost a perfect score in chemistry. I relied on this mind map summarizing the key and difficult points in chemistry in the college entrance examination. Now I share it with you! I hope to be helpful!
Edited at 2021-01-13 16:40:05Find a streamlined guide created using EdrawMind, showcasing the Lemon 8 registration and login flow chart. This visual tool facilitates an effortless journey for American users to switch from TikTok to Lemon 8, making the transition both intuitive and rapid. Ideal for those looking for a user-centric route to Lemon 8's offerings, our flow chart demystifies the registration procedure and emphasizes crucial steps for a hassle-free login.
これは稲盛和夫に関するマインドマップです。私のこれまでの人生のすべての経験は、ビジネスの明確な目的と意味、強い意志、売上の最大化、業務の最小化、そして運営は強い意志に依存することを主な内容としています。
かんばんボードのデザインはシンプルかつ明確で、計画が一目で明確になります。毎日の進捗状況を簡単に記録し、月末に要約を作成して成長と成果を確認することができます。 実用性が高い:読書、早起き、運動など、さまざまなプランをカバーします。 操作簡単:シンプルなデザイン、便利な記録、いつでも進捗状況を確認できます。 明確な概要: 毎月の概要により、成長を明確に確認できます。 小さい まとめ、今月の振り返り掲示板、今月の習慣掲示板、今月のまとめ掲示板。
Find a streamlined guide created using EdrawMind, showcasing the Lemon 8 registration and login flow chart. This visual tool facilitates an effortless journey for American users to switch from TikTok to Lemon 8, making the transition both intuitive and rapid. Ideal for those looking for a user-centric route to Lemon 8's offerings, our flow chart demystifies the registration procedure and emphasizes crucial steps for a hassle-free login.
これは稲盛和夫に関するマインドマップです。私のこれまでの人生のすべての経験は、ビジネスの明確な目的と意味、強い意志、売上の最大化、業務の最小化、そして運営は強い意志に依存することを主な内容としています。
かんばんボードのデザインはシンプルかつ明確で、計画が一目で明確になります。毎日の進捗状況を簡単に記録し、月末に要約を作成して成長と成果を確認することができます。 実用性が高い:読書、早起き、運動など、さまざまなプランをカバーします。 操作簡単:シンプルなデザイン、便利な記録、いつでも進捗状況を確認できます。 明確な概要: 毎月の概要により、成長を明確に確認できます。 小さい まとめ、今月の振り返り掲示板、今月の習慣掲示板、今月のまとめ掲示板。
Summary of key and difficult points in college entrance examination chemistry
Chemistry knowledge point 1
Alkaline substances
①Alkaline: NaOH, NH3·H2O, NaHCO3, Na2CO3, NaAlO2, Na2SiO3, etc.
②Alkaline oxidation: Na2O2, NaClO, NaNO2, Fe(OH)3, etc.
③Alkaline reduction: Na2SO3, Na2S, Fe(OH)2, etc.
Acidic substances
①Acidity: HCl (dilute), H2SO4 (dilute), H2CO3, NaHSO4, AlCl3, NH4Cl, etc.
②Acidic oxidizing properties: HNO3, H2SO4 (concentrated), HClO, FeCl3, CuSO4, etc.
③Acidity and reduction: H2S, H2SO3, HI, FeSO4, etc.
Neutral substances:
①Neutral: Na2SO4, CaCl2, Ba(NO3)2, etc.
②Neutral reducing property: NaI, KBr, etc.
When acids, alkalis and neutral substances react
(1) Metathesis reaction that generates precipitation occurs
H2SO4 Ba(NO3)2=BaSO4↓ 2HNO3
For example: CaCl2 Na2CO3=2NaCl BaCO3↓
(2) Oxidation-reduction reaction occurs
For example: 2NaI Na2O2 2H2O=4NaOH I2
2NaI 2FeCl3=2FeCl2 2NaCl I2
The more difficult ones are the following two types of reactions:
①The reaction between a substance that is both acidic and oxidizing and a substance that is both alkaline and reducing;
②The reaction between a substance that is both acidic and reducing and a substance that is both alkaline and oxidizing
Chemistry knowledge point 2
1. Impurity conversion method
To remove phenol from benzene, add sodium hydroxide
Convert phenol into sodium phenolate, using sodium phenolate to be easily soluble in water
separate it from benzene
To remove NaHCO3 from Na2CO3, you can use heating
2. Absorption washing method
To remove a small amount of hydrogen chloride and water mixed in carbon dioxide
The mixed gas can be passed through a saturated sodium bicarbonate solution first and then
through concentrated sulfuric acid
3. Precipitation filtration method
To remove a small amount of copper sulfate mixed in ferrous sulfate solution
Add excess iron powder
After sufficient reaction
Filter to remove insoluble matter
4. Heating sublimation method
To remove sand from iodine
5. Solvent extraction method
To remove small amounts of bromine contained in water
6. Solution crystallization method (crystallization and recrystallization)
To remove a small amount of sodium chloride from sodium nitrate solution
The difference in solubility between the two can be used
Lower solution temperature
Crystallize sodium nitrate to obtain pure crystals of sodium nitrate
7. Fractionation and distillation methods
To remove a small amount of alcohol from ether
Multiple distillation methods can be used
Distillation can be used to separate the extracted iodine and benzene.
8. Liquid separation method
This method can be used to separate liquid mixtures with different densities that are immiscible, such as benzene and water.
9. Dialysis
To remove ions from colloids, this method can be used
For example, removing chloride ions from ferric hydroxide colloid
10. Comprehensive method
To remove impurities from a substance, you can use the above methods or a combination of methods
Chemistry knowledge point 3
Nitric oxide and nitrogen dioxide
Nitric oxide is formed in nature by high temperature or electric discharge.
N2 O2 (concentrated H2SO4) 12C 11H2O exothermic
2H2SO4 (concentrated) CCO2↑ 2H2O SO2↑
It can also oxidize metals ranked behind hydrogen, but does not release hydrogen.
2H2SO4 (concentrated) CuCuSO4 2H2O SO2↑
dilute sulfuric acid
Reacts with active metals to release H2, turning the acid-base indicator purple litmus red.
React with certain salts, react with alkaline oxides, neutralize with bases
Nitric acid
Physical properties: Colorless liquid, easily volatile, with a lower boiling point and a higher density than water.
Chemical properties: It has the properties of general acids. Concentrated nitric acid and dilute nitric acid are both strong oxidants. It can also oxidize metals ranked behind hydrogen, but does not release hydrogen gas.
4HNO3(concentrated) Cu==Cu(NO3)2 2NO2↑ 4H2O
8HNO3(dilute) 3Cu3Cu(NO3)2 2NO↑ 4H2O
Depending on the reaction conditions, the products obtained by the reduction of nitric acid are different.
N(4)O2,HN(3)O2,N(2)O,N(1)2O,N(0)2,N(-3)H3△
Iron-aluminum containers can hold cold concentrated sulfuric acid and concentrated nitric acid
Nitric acid and sulfuric acid are both important chemical raw materials and essential reagents in laboratories.
Can be used to make fertilizers, pesticides, explosives, dyes, salts, etc.
Sulfuric acid is also used for refining petroleum, pickling before metal processing and preparing various volatile acids.
Chemistry knowledge point 4
Types of reactions that may occur with hydroxyl functional groups
Substitution (alcohol, phenol, carboxylic acid)
Eliminate (alcohol)
Esterification (alcohols, carboxylic acids);
Oxidation (alcohol, phenol)
Polycondensation (alcohol, phenol, carboxylic acid)
Neutralization reaction (carboxylic acid, phenol)
Diols with the molecular formula C5H12O2 have 2 structures with 3 carbon atoms in the main chain.
CH4O and C3H8O are dehydrated under the action of concentrated sulfuric acid, and up to 7 organic products can be obtained
Alkenes with a molecular composition of C5H10 have 5 possible structures.
There are 7 kinds of ester substances with a molecular formula of C8H14O2 and a six-membered carbon ring in their structure.
When equal masses of methane, ethylene, and acetylene are fully burned, the amount of oxygen consumed is from greater to less
The main components of cotton and rayon are cellulose
The application of substitution, addition, reduction, oxidation and other reaction types may introduce hydroxyl groups into organic molecules.
Chemistry knowledge point 5
Metal activity - the ability of metal atoms to lose electrons in aqueous solution
1. The ease and intensity of the reaction between metal elements and water under certain conditions. Generally speaking, the easier and more violent the reaction with water, the stronger its metallicity.
2. The difficulty and intensity of reaction with acid of the same concentration at room temperature. Generally speaking, the easier and more violent the reaction with acid is, the stronger its metallicity is.
3. Based on the alkalinity of the hydrate of the valent oxide. The stronger the base, the more metallic its element.
4. Based on the replacement reaction between metal elements and salt solutions. Generally, active metals replace inactive metals. However, when metals from Groups IA and IIA react with salt solutions, they usually react with water to generate corresponding strong bases and hydrogen, and then the strong bases may undergo metathesis reactions with the salts.
5. According to the metal activity sequence table (with rare exceptions).
6. According to the periodic table of elements. In the same period, from left to right, as the nuclear charge increases, the metallicity gradually weakens; in the same main group, from top to bottom, as the nuclear charge increases, the metallicity gradually increases.
7. According to the electrode names in the original battery. The metallicity of the negative electrode material is stronger than that of the positive electrode material.
8. Based on the discharge (electron gain, oxidation) sequence of cations in the electrolytic cell. The cations that are discharged preferentially have weak metallicity.
9. The less energy a gaseous metal atom consumes when losing electrons and becoming a stable structure, the stronger its metallicity.
"Metallicity" and "metallic mobility" are not the same concepts
The two are sometimes expressed as inconsistent
Such as Cu and Zn: metallicity is: Cu>Zn, and metal activity is: Zn>Cu
Chemistry knowledge point 6
Chemical equation for decomposition reaction with oxygen production
Heating potassium chlorate (with a small amount of manganese dioxide): 2KClO3=MnO2△=2KCl 3O2↑
Heating potassium permanganate: 2KMnO4=△=K2MnO4 MnO2 O2↑
Heating potassium permanganate: 2KMnO4=△=K2MnO4 MnO2 O2↑
Water is divided into 2H2O under the action of direct current = energization = 2H2↑ O2↑
Laboratory use of hydrogen peroxide to produce oxygen: 2H2O2=MnO2=2H2O O2↑
Heating mercury oxide: 2HgO=△=2Hg O2↑
How to calculate the degree of unsaturation
1. When the molecular formula of the organic compound is known
(1), for general organic compounds containing only C, H, and O, the formula can be used
Ω=(number of carbon atoms × 2 2 - number of hydrogen atoms)/2, the meaning of the formula is half the difference between the number of hydrogen atoms in an alkane or alcohol with the same number of carbon atoms and the number of hydrogen atoms in the organic matter, that is, 1 mol of the organic matter The amount of H2 consumed for complete hydrogenation reduction to alkanes or alcohols;
(2) For organic compounds containing trivalent atoms such as N and P (excluding nitro compounds or phosphoryl compounds), they can be supplemented with (NH) or (PH), and then the formula can be applied;
(3) For organic substances substituted by halogen atoms, the halogen atoms can be converted into hydrogen atoms first and then the formula can be applied;
(4) For allotropes of carbon (such as C60), the number of hydrogen atoms can be regarded as 0, and then the formula can be applied.
2. When the structure of organic matter is known
(1)Ω=number of double bonds, number of triple bonds × 2 number of rings, that is, a double bond and a ring both lack one hydrogen, and a triple bond lacks two hydrogens. The benzene ring can be regarded as a double bond plus a ring, and its degree of unsaturation is 4; after calculating the degree of unsaturation, the hydrogen can be calculated by using the deformation of the formula number of hydrogen atoms = number of carbon atoms × 2 2 - degree of unsaturation × 2 number of atoms;
(2) The structure contains trivalent atoms such as N and P (excluding nitro or phosphoryl groups). After calculating the degree of unsaturation, the number of N and P atoms should be added to the number of hydrogen atoms obtained; in the structure Containing halogen atoms, the number of hydrogen atoms obtained should be subtracted from the number of halogen atoms.
Derivation of isomers of organic matter
1. Determine the number of carbon atoms of the organic substance and find the degree of unsaturation of the organic substance. Make a rough judgment based on the obtained degree of unsaturation.
2. Analyze known conditions and determine the basic types of organic matter. Generally speaking, a degree of unsaturation can correspond to a carbon-carbon double bond, a carbonyl group (aldehyde group) or a ring; when the degree of unsaturation of an organic substance is greater than 4, the benzene ring is first considered; and then the analysis given in the question Conditions, such as "silver mirror reaction can occur", "can react with NaHCO3 solution", "amount of NaOH consumed, etc.", determine the functional groups in the organic matter.
3. Determine the structure of the carbon chain and the position of the substituents. Pay special attention to the symmetry factors in the molecule, such as "there are several monohalogenated compounds" and "there are several C and N atoms in different environments" given in the question, so as to determine the structure of the isomer.
4. Test the obtained isomer to confirm that its molecular formula is the same as the original organic compound and meets the conditions in the question.
Basic types of organic reactions
Substitution reaction
A reaction in which an organic compound is attacked by a certain type of reagent and a group (or atom) in the molecule is replaced by this reagent.
A substitution reaction must satisfy the form of A(B)=CD, that is, there may not be multiple reactants, but there are at least two products; the halogenation, nitration, sulfonation, esterification, and various hydrolysis learned in high school Reactions such as the formation of peptide bonds from amino acids and the intramolecular dehydration of alcohols are all substitution reactions.
addition reaction
Definition: A reaction in which the heavy bonds in organic compounds are opened and the atoms at both ends are each connected to a new group.
In addition reactions, the unsaturation of organic matter will generally decrease (except for the reaction of double bond isomerization to form rings). Common addition reactions include: hydrogenation and halogen addition (note the 1,2 addition and 1,4 addition of dienes). into), add HX, add water, etc.
elimination reaction
Definition: A reaction in which a reactant molecule loses two groups or atoms, thereby increasing its degree of unsaturation.
The products of the elimination reaction must be more than two, one of which is often a small molecule (H2O, HX), etc. The two elimination reactions (alcohols and halogenated hydrocarbons) learned in high school are both β-elimination reactions. The organic matter that reacts must have β-H atoms, that is, the H atoms at the ortho-C position of the functional group. Note that when an asymmetric compound undergoes an elimination reaction, there are often multiple reaction orientations, and the resulting compound is a mixture.
Redox reactions
In organic reactions, the reaction in which hydrogen is gained or oxygen is lost is called a reduction reaction, and the reaction in which hydrogen is lost or oxygen is gained is called an oxidation reaction.
Different from the redox reaction in inorganic chemistry, the redox reaction of organic matter generally only targets the organic matter participating in the reaction without discussing the inorganic reagents used, so the two are separated in the organic reaction type.
Common oxidation reactions include: catalytic oxidation with oxygen (catalysts are Cu, Ag, etc.), reaction of olefins, benzene homologues and potassium permanganate solution, ozonation and epoxidation of olefins, silver mirror reaction of aldehydes, aldehydes Reaction with newly prepared Cu(OH)2, etc.
The reduction reactions learned in high school include the catalytic hydrogenation reaction of aldehydes and ketones, and the reduction reaction of nitro group to amino group.
Polymerization
A reaction that combines one or more substances with simple small molecules into substances with large molecular weight.
The polymerization reactions learned in high school include addition polymerization and condensation polymerization. The former refers to the reaction in which unsaturated compounds form polymers through mutual addition; the latter refers to the multiple condensations between multifunctional monomers.
Reactions that release low-molecular by-products at the same time. The difference between the two is whether there are small-molecule by-products.
Chemistry knowledge point 7
N2: Synthetic ammonia, fills bulbs (with argon), preserves grain
Rare gases—protective gas, neon lights, lasers
H2 sounding balloon, hydrogen-oxygen flame, metallurgy, synthetic ammonia, high-energy harmless fuel
CO2 fire extinguishing agent, soda ash production, urea production, artificial rainfall (dry ice)
C. Diamond: for making drill bits and graphite: for making electrodes, crucibles, pencil leads, and high-temperature lubrication
C. Diamond: to make drill bits, graphite: to make electrodes, crucibles, pencil leads, high-temperature lubricants
Charcoal black gunpowder; coke metallurgy; carbon black oil black, pigments, rubber wear-resistant additives
CaCO3: building stone, concrete, ironmaking flux, cement making, glass making, lime making
Cl2: tap water disinfection, hydrochloric acid production, bleaching powder production, chloroform production
AgBr: photosensitive material; AgI: artificial rainfall
S: Make sulfuric acid, vulcanize rubber, make black powder, make pesticide lime sulfur mixture, make sulfur ointment to treat skin diseases
P: White phosphorus is used to make high-purity phosphoric acid, red phosphorus is used to make pesticides, matches, and smoke bombs.
Si: making alloys and making semiconductors.
.SiO2: optical fiber, quartz glass, ordinary glass
Mg, Al alloy, aluminum wire, thermite
MgO, Al2O3: refractory materials, Al2O3 is used to make metal aluminum
Alum: water purifier;
Bleach: chlorine, bleaching powder (essentially HClO); SO2 (or H2SO3); Na2O2; H2O2; O3
Disinfection and sterilization: chlorine, bleaching powder (water disinfection); potassium permanganate (dilute solution skin disinfection), alcohol (skin, 75%), iodine;
BaSO4: Medical “barium meal”
Semiconductors: selenium, silicon, germanium Ge, gallium Ga
K, Na alloy, thermal conductive agent for atomic energy reactors; thermonuclear materials made of lithium, photoelectric tubes made of rubidium and cesium
Baking soda to treat hyperacidity
MgCl2 makes metallic magnesium (electrolysis), Al2O3 makes metallic aluminum (electrolysis), NaCl makes metallic sodium (electrolysis)
Ethylene, a fruit ripening agent and a symbol of petrochemical industry level
Gas welding, gas cutting oxygen acetylene flame, hydrogen-oxygen flame
Ethylene glycol is used to resist freezing in internal combustion engines
Glycerin is used to make nitroglycerin, solvents, and lubricants