Chengdu Xueda Education, with its first-class teachers, professional service team, advanced teaching guidance system and perfect teaching management mode, has helped tens of thousands of students achieve breakthrough in their grades and successfully entered ideal junior high schools and universities, winning praise from many parents and society.
Scoring hotline: 400-0 12-4008.
I. Scientific names, common names and chemical formulas of common substances
Common name? Scientific name? chemical formula
Diamond, graphite? C
Alcohol? Ethanol? C2H5OH
Hydrated lime, hydrated lime? Calcium hydroxide? calcium hydroxide
Quicklime? Calcium oxide? Chief administrative officer
Acetic acid (melting point 16.6℃, solid is called glacial acetic acid)? CH3COOH acetate
Lignol? Lignol? Methanol? methyl alcohol
Dry ice? Solid carbon dioxide? carbon dioxide
Tongluo, malachite? Basic copper carbonate? Cu2(OH)2CO3
Bile alum, blue alum? Copper sulfate crystal? CuSO4？ 5H2O
Hydrosulfuric acid? H2S
Sulfuric acid? sulphuric acid
Salt water (industrial name)? Hydrochloric acid? Hydrochloric acid? Highcostofliving
Mercury? Mercury? mercury
Soda, soda, surface alkali? Sodium carbonate? soda
Soda crystals Sodium carbonate crystal? Na2CO3？ 10H2O
Acid sodium carbonate and baking soda? Sodium bicarbonate? sodium bicarbonate
Caustic soda, caustic soda, caustic soda? Sodium hydroxide? sodium hydroxide
Toxic salts and nitrates (industrial names)? Sodium nitrite? Sodium nitrite
Ammonia? Ammonia monohydrate? NH3？ H2O
Second, the color and state of common substances
1, white solid: MgO, P2O5, CaO,? NaOH, Ca(OH)2, KClO3, KCl, Na2CO3, NaCl and anhydrous CuSO4；; Iron and magnesium are silvery white (mercury is silvery white liquid)
2. Black solid: graphite, carbon powder, iron powder, CuO, MnO2, Fe3O4, KMnO4 is purple-black.
3. Red solid: Cu, Fe2O3? , HgO, red phosphorus
4. Pale yellow: sulfur.
5. Green: Cu2(OH)2CO3 is green.
6. Color of solution: Any solution containing Cu2+ is blue; Any solution containing Fe2+ is light green; Any solution containing Fe3+ is brownish yellow, and other solutions are generally colorless. (Potassium permanganate solution is purplish red)
7. Precipitation (that is, salt and alkali are insoluble in water): ① Salt: white ↓:CaCO3, BaCO3 (soluble in acid)? AgCl, BaSO4 (also insoluble in dilute HNO3)? Iso2 alkali: blue precipitate: Cu(OH)2? ; Red-brown precipitate: Fe(OH)3, white precipitate: the rest is alkali.
8.( 1) Gases with irritating gases: NH3, SO2 and HCl (all colorless).
(2) Colorless and odorless gases: O2, H2, N2, CO2, CH4 and CO (highly toxic).
Note: liquids with pungent odor: hydrochloric acid, nitric acid and acetic acid. Alcohol is a liquid with a special gas.
9. Toxic gas: carbon monoxide? Liquid: CH3OH? Solid: NaNO2, CuSO4 (can be used as bactericide? , mixed with hydrated lime to make a blue viscous substance-Bordeaux liquid).
Third, the solubility of substances.
1, salt solubility
Substances containing potassium, sodium, nitrate and ammonium are all soluble in water.
Only AgCl and HgCl are insoluble in water, and others are soluble in water.
Contains SO42-? The only compound is BaSO4? PbSO4 is insoluble in water, AgSO4 is slightly soluble in water, and others are soluble in water.
Contains CO32? Only K2CO3, Na2CO3 and (NH4)2CO3 are soluble in water, while others are insoluble in water.
2. Solubility of alkali
Alkalis soluble in water include barium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydroxide and ammonia water, while other alkalis are insoluble in water. Fe(OH)3 is red-brown precipitate, Cu(OH)2 is blue precipitate, and other insoluble bases are white. (including iron hydroxide)
Note: AgCl and BaSO4 in sediments? Insoluble in dilute nitric acid, other precipitates are soluble in acid. Such as: Mg(OH)2? CaCO3？ BaCO3。 And others.
3. Acids and acidic oxides are mostly soluble in water, while (acidic oxide+water → acid) basic oxides are mostly insoluble in water and partially soluble: barium oxide, potassium oxide, calcium oxide and sodium oxide (basic oxide+water → alkali). There is a formula to help students remember these things: potassium, sodium, ammonium and nitrate are all soluble, but hydrochloric acid is insoluble in silver and mercury; Sulfate does not dissolve barium and lead, and carbon phosphate is mostly insoluble; Most acids are soluble in alkali, but only potassium, sodium, ammonium and barium are soluble.
Fourth, chemistry is the most.
1. The most abundant metal element in the earth's crust is aluminum.
2. Oxygen is the most abundant nonmetallic element in the earth's crust.
The most abundant substance in the air is nitrogen.
The hardest substance in nature is diamond.
5. The simplest organic matter is methane.
6. The most active metal in the metal activity sequence table is potassium.
7. The oxide with the smallest relative molecular mass is water.
8. The simplest organic compound CH4.
9. Under the same conditions, the gas with the lowest density is hydrogen.
10, the most conductive metal is silver.
1 1, and the atom with the smallest relative atomic mass is hydrogen.
12, and the metal with the smallest melting point is mercury.
13, the most abundant element in human body is oxygen.
14, the element that constitutes the most kinds of compounds is carbon.
15, the most widely used metal in daily life is iron.
16, the only nonmetallic liquid element is bromine;
17, China first used natural gas;
18. The largest coal base in China is: Shanxi Province;
19, the earliest use of wet copper smelting is China (found in the Western Han Dynasty [Liu An's Huainan Wanbi Shu] "Zeng Qing gained iron and turned copper"? ], song dynasty application);
20, the earliest discovery of electrons is Thomson in Britain;
2 1, lavoisier was the first to draw the conclusion that air is composed of N2 and O2.
Five, "certain" and "not necessarily" in chemistry
1, chemical changes must have physical changes, and physical changes may not necessarily have chemical changes.
2. Metals are not always solid at room temperature (for example, Hg is liquid), and nonmetals are not always gas or solid (for example, Br2? Note: Metals and nonmetals refer to simple materials and should not be confused with the constituent elements of matter.
3, the atomic group must be charged ions, but the atomic group is not necessarily an acid radical (such as NH4+? Oh-? ); ? Acid radical is not necessarily an atomic group, is it? (for example? Cl-？ Called hydrochloride).
4. Slow oxidation may not cause spontaneous combustion. Combustion must be a chemical change. The explosion is not necessarily a chemical change. (For example, the explosion of a pressure cooker is a physical change. )
There are not always neutrons in the nucleus (for example, there are no neutrons in the H atom).
6. Atoms are not necessarily smaller than molecules. ? The fundamental difference between molecules and atoms is that in chemical reactions, molecules can be separated and atoms cannot be separated.
7. A substance composed of the same element is not necessarily a simple substance, but may be a mixture of several simple substances. Such as O2 and O3.
8. Particles with the outermost electron number of 8 are not necessarily atoms of rare gas elements, but may also be cations or anions.
9. The outermost electron number of atoms with stable structure is not necessarily 8, such as helium atoms. The first layer is the outermost two electrons.
10, particles with the same nuclear charge number are not necessarily the same element. ? (Because particles include atoms, molecules and ions, while elements do not include molecules or atomic groups composed of polyatomic atoms) Only those with the same nuclear charges? Mononuclear particles? (An atom and a nucleus) must belong to the same element.
1 1 and (1) concentrated solutions are not necessarily saturated solutions; A dilute solution is not necessarily an unsaturated solution. (For different solutes) (2) A saturated solution of the same substance is not necessarily thicker than an unsaturated solution. (Because the temperature is uncertain, just as the temperature is certain) (3) The solution after crystal precipitation must be a saturated solution of something. After the saturated solution is cooled, the crystal does not necessarily precipitate. (4)? At a certain temperature, the solubility of any substance must be greater than the solute mass fraction of its saturated solution, that is? S must be greater than c? .
12, the reaction between simple materials and the compound is not necessarily a displacement reaction. But the valence of elements must have changed.
13, the valence of elements does not necessarily change in decomposition reaction and combination reaction; The valence of elements must change in the displacement reaction; In the metathesis reaction, the valence of elements must remain unchanged. (? Note: the valence of elements must change in redox reaction? )
14, simple substance must not be decomposed.
15, the same element does not necessarily show a valence in the same compound. Like NH4NO3? (front n is -3 and back n is +5).
16, the composition of salt does not necessarily contain metal elements. For example, NH4+ is a cation with the properties of metal ions, but it is not a metal ion.
17. Cations are not necessarily metal ions. Like H+? 、NH4+？ .
18, in the composition of compounds (oxide, acid, alkali, salt), oxide and alkali must contain oxygen; Acids and salts do not necessarily (possibly) contain oxygen; Acids and bases must contain hydrogen; It is salts and oxides that do not necessarily contain hydrogen; The composition of salt and alkali does not necessarily contain metal elements (such as NH4NO3? 、NH3？ 、H2O)； Acid components may contain metal elements (such as HMnO4? This is called permanganate. But all substances must contain nonmetallic elements? .
19, the salt solution is not necessarily neutral. Like Na2CO3? The solution is alkaline.
20、? The solution of acid salt is not necessarily acidic? (that is, the PH value is not necessarily less than 7), such as NaHCO3 solution is alkaline. But the sodium bisulfate solution is acidic, so the substance that can ionize hydrogen ions is not necessarily acid.
2 1、? The acid solution must be an acid solution, but the acid solution is not necessarily an acid solution, such as H2SO4? 、NaHSO4？ The solution is acidic, and? NaHSO4？ It belongs to salt. ? The acidic solution is an acidic aqueous solution, and the acidic solution is a solution containing H+.
22、? The alkaline solution must be an alkaline solution, but the alkaline solution is not necessarily an alkaline solution. Such as NaOH, Na2CO3? , NaHCO3 solution is alkaline, while Na2CO3? 、NaHCO3？ For salt? . ? The alkaline solution is an aqueous solution of alkali, and the alkaline solution is a solution containing OH-).
23. Basic oxides must be metal oxides, and metal oxides are not necessarily basic oxides. (for example? Mn2O7 is a metal oxide, but it is an acid oxide, and the corresponding acid is permanganate, that is, HMnO4? ); Remember: only K2O, Na2O, BaO and CaO in basic oxides can be dissolved in water and react with water to form alkali.
24、? Acid oxides are not necessarily nonmetallic oxides (such as Mn2O7? ), nonmetallic oxides are not necessarily acidic oxides (such as H2O, CO, NO). ? ★ Common acidic oxide: CO2? 、? SO2？ 、? SO3？ 、P2O5？ 、? Silicon dioxide? And so on, most acidic oxides can be dissolved in water and react with water to generate corresponding acids. Remember silicon dioxide (SiO2? ) insoluble in water? .
25. The reaction between salt and water is not necessarily a neutralization reaction.
26. All chemical reactions do not necessarily belong to the basic reaction type. Those that do not belong to the basic reaction are: ① the reaction between co and metal oxides; (2) the reaction of acid oxide with alkali; ③ Combustion of organic matter.
27. All elemental iron participates in the displacement reaction (iron reacts with acid and salt), and the iron after the reaction must be +2 valence (i.e. ferrous salt is generated).
28. Where there is a displacement reaction between metal and acid, the quality of the solution will inevitably increase after the reaction. ? When a metal reacts with a salt solution, we can judge the quality change of the solution before and after the reaction only by looking at the relative atomic mass of the metal participating in the reaction and the relative atomic mass of the metal generated. "Big for small weight gain, small for big weight loss".
29. When metals with the same mass and valence react with acids, the greater the relative atomic mass, the less hydrogen is produced.
30. Any metal (such as K, Ca, Na) that can react with water at room temperature shall not be replaced by salt solution; But they react most violently with acids. ? Like what? Na joined CuSO4? What is the reaction in the solution? :? 2Na+2H2O？ =2NaOH+H2？ ↑; 2NaOH+CuSO4？ =Cu(OH)2？ ↓+Na2SO4？ .
3 1. All exhaust methods (upward or downward) must extend the air duct to the bottom of the gas container.
32, preparation of gas generator, be sure to check the air tightness before charging. ? Be sure to check the purity of combustible gas before ignition or heating? .
33. When writing a chemical formula, all positive valence elements are not necessarily written on the left. Like NH3? 、CH4。
34, 5g of a substance into 95g of water, fully dissolved, the solute mass fraction of the solution is not necessarily equal to 5%.
May be equal to? 5%, such as NaCl and KNO3? Wait; May also be greater than 5%, such as, Na2O, abalone,? Wait; It may also be less than 5%, such as crystalline hydrate and Ca(OH)2? Cao? Wait a minute.
◆ Under the same conditions, Cao or Ca(OH)2? The solute mass fraction of the solution obtained after being dissolved in water is the smallest.
Address of each campus in Chengdu:
Skydiving Tower: World Commercial Plaza, No.85 Zizhu North Street, Chengdu 1F
Babao Street: 8th Floor, Guo Xin Plaza, No.28 Genxia Street, Dongcheng 10 (opposite Carrefour)
Shuangnan: No.5, No.5 and No.6 (New Hope Hongnan Port), West Section 1, Second Ring Road, Wuhou District, Chengdu.
Jinsha: 3rd floor, Building 5, Jinfeng Road 13, Qingyang District (opposite to the fire brigade)
HKUST: Floor 2, No.6, Longhu Sanqianli Phase II, East Second Section of Second Ring Road 1 Store.
Shuangliu: Floor 3, Tonglan Building, Nanchang Road, Shuangliu County, Chengdu
Daci Temple: No.2, Floor 2, Building No.7 1 Tianxianqiao North Road, Jinjiang District, Chengdu
Jiangxi Street: Floor 2, Nongzi Building, Jinli East Road 10, Qingyang District, Chengdu.
Xueda Education (Chengdu Jiangxi Street Campus)
Address: 2nd Floor, Ground Floor, Nongzi Building, Jinli East Road 10 (No.2 Shangchi North Street)