Chemical formula of commonly used substances in junior high school
Hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur and chlorine (nonmetallic elements)
H2 C N2 O2 P S Cl2
Sodium, magnesium, aluminum, potassium, calcium, iron, zinc, copper, barium, tungsten and mercury (simple metals)
Na Mg Al K Ga Fe Zn Cu Ba W Hg
Water, carbon monoxide, carbon dioxide, sodium diphosphate pentoxide, nitrogen dioxide and silicon dioxide.
H2O, carbon monoxide, carbon dioxide, P2O5, Na2O2SiO2.
Sulfur dioxide, sulfur trioxide, nitric oxide, magnesium oxide, copper oxide, barium oxide and cuprous oxide.
SO2 SO3 NO MgO CuO BaO Cu2O
Ferrous oxide, iron oxide (iron red), iron oxide, alumina and tungsten oxide.
Iron oxide iron oxide ferric oxide aluminum oxide WO3
Silver oxide, lead oxide and manganese dioxide (common oxides)
Ag2O PbO MnO2
Potassium chloride sodium chloride (salt) magnesium chloride calcium chloride copper chloride zinc chloride barium chloride aluminum chloride
KCl sodium chloride magnesium chloride calcium chloride copper chloride zinc chloride barium chloride aluminum trichloride
Ferrous chloride, ferric chloride and silver chloride (chloride/hydrochloride)
Ferric chloride, ferrous chloride and silver chloride
Sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrogen sulfide and bromobicarbonate (common acid)
Sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, H2S, bicarbonate bromide.
Copper sulfate, barium sulfate, calcium sulfate, potassium sulfate, magnesium sulfate, ferrous sulfate and ferric sulfate.
Copper sulfate, barium sulfate, calcium sulfate, potassium sulfate, magnesium sulfate, ferrous sulfate, ferric sulfate
Aluminum sulfate, sodium bisulfate, potassium bisulfate, sodium sulfite, sodium nitrate, potassium nitrate and silver nitrate.
Al2(SO4)3 nah so 4 khso 4 naso 3 nano 3 kno 3 agno 3
Magnesium nitrate, copper nitrate, calcium nitrate, sodium nitrite, sodium carbonate, calcium carbonate and magnesium carbonate.
Magnesium nitrate copper calcium nitrate sodium nitrite sodium carbonate calcium carbonate magnesium carbonate
Potassium carbonate (salt)
potassium carbonate
Sodium hydroxide, calcium hydroxide, barium hydroxide, magnesium hydroxide, copper hydroxide, potassium hydroxide and aluminum hydroxide.
Sodium hydroxide ca (oh) 2ba (oh) 2mg (oh) 2cu (oh) 2koal (oh) 3
Iron hydroxide and ferrous hydroxide (common alkali)
ferrous hydroxide
Methane acetylene methanol ethanol acetic acid (common organic matter)
Methane C2H2 CH3OH C2H5OH CH3COOH
Basic copper carbonate gypsum plaster alum copperas.
Cu2(OH)2CO3 CaSO4？ 2H2O 2 CaSO4？ H2O· Karl (sulfuric acid) 2? 12H2O FeSO4？ 7H2O
Blue alum sodium carbonate crystal (common crystal hydrate)
CuSO4？ 5H2O Na2CO3？ 10H2O
Urea, ammonium nitrate, ammonium sulfate, ammonium bicarbonate and potassium dihydrogen phosphate (common fertilizer)
CO(NH2)2 nh4no 3(NH4)2so 4 NH 4h CO 3 kh2po 4
Precipitation:
Red-brown flocculent precipitate -Fe (OH) 3
Light green precipitate-iron hydroxide
Blue flocculent precipitate-copper hydroxide
White precipitate-CaCO3, baco3, AgCl, BaSO4, (baso4 and AgCl are white precipitate insoluble in HNO3, CaCO3 BaCO3 is white precipitate soluble in HNO3), Mg(OH)2.
Pale yellow precipitate (in aqueous solution)-S.
Slightly soluble in water -ca (oh) 2, caso4.
Summary of junior high school chemical equation
A, the nature of oxygen:
(1) Reaction of simple substance with oxygen: (combination reaction)
1. Magnesium burns in air: 2Mg+O2 ignites 2MgO.
2. Iron burns in oxygen: 3Fe+2O2 ignites Fe3O4.
3. Copper heating in air: 2Cu+O2 heating 2CuO.
4. Aluminum burns in air: 4Al+3O2 ignites 2Al2O3.
5. Combustion in hydrogen and air: 2H2+O2 ignites 2H2O.
6. Red phosphorus burns in air (experiment to study air composition): 4P+5O2 ignites 2P2O5.
7. Sulfur powder burns in air: S+O2 ignites SO2.
8. Complete combustion of carbon in oxygen: C+O2 ignites CO2.
9. Incomplete combustion of carbon in oxygen: 2C+O2 ignites 2CO.
(2) the reaction of compounds with oxygen:
10. Carbon monoxide burns in oxygen: 2CO+O2 ignites 2CO2.
1 1. Methane burns in air: CH4+2O2 ignites CO2+2H2O.
12. Alcohol burns in air: C2H5OH+3O2 ignites 2CO2+3H2O.
(3) Oxygen source:
13. Boyle studies the composition of air experiment 2HgO heating Hg+O2 =
14. heating potassium permanganate: 2KMnO4 heating k2mno4+MnO2+O2 = (principle of oxygen production in laboratory 1)
15. decomposition reaction of hydrogen peroxide with manganese dioxide as catalyst: H2O2, MnO, 22h2o+O2 = (principle of oxygen production in laboratory 2)
Second, the water in nature:
16. Decomposition of water under the action of direct current (experimental study on composition of water): 2H2O electrified 2H2 =+O2 =
17. quicklime is soluble in water: CaO+H2O == Ca(OH)2.
18. Carbon dioxide is soluble in water: H2O+CO2==H2CO3.
Third, the law of conservation of mass:
19. Magnesium burns in air: 2Mg+O2 ignites 2MgO.
20. The reaction between iron and copper sulfate solution: Fe+CuSO4 = = FeSO4+Cu.
2 1. Reduction of copper oxide by hydrogen: H2+ copper oxide heats copper +H2O.
22. Magnesium reduces copper oxide: magnesium+copper oxide heats copper+magnesium oxide.
Four, carbon and carbon oxides:
Chemical properties of (1) carbon
23. Carbon burns completely in oxygen: C+O2 ignites CO2.
24. Reduction of copper oxide with charcoal: 2Cu, high temperature 2Cu+CO2↑ =
25. Reduction of iron oxide by coke: 3C+ 2Fe2O3, high temperature 4Fe+3CO2↑ =
(2) Three reactions in coal furnace: (several combined reactions)
26. Bottom of coal stove: C+O2 ignites CO2.
27. Middle layer of coal furnace: CO2+C high temperature 2CO.
28. Blue flame in the upper part of coal stove: 2CO+O2 ignites 2CO2.
(3) Preparation and properties of carbon dioxide:
29. Marble reacts with dilute hydrochloric acid (carbon dioxide made in the laboratory):
CaCO3 + 2HCl == CaCl2 + H2O + CO2
30. Carbonic acid is unstable and decomposed: H2CO3 == H2O+CO2↑ =
3 1. Carbon dioxide dissolved in water: H2O+CO2== H2CO3
32. Calcined limestone at high temperature (industrial carbon dioxide production): CaCO3, high temperature CaO+CO2↑ =
33. Lime water and carbon dioxide reaction (carbon dioxide identification):
Calcium hydroxide+carbon dioxide = = calcium carbonate ↓+ H2O
(4) Properties of carbon monoxide:
34. Reduction of copper oxide by carbon monoxide: CO+ CuO heats Cu+CO2.
35. Combustibility of carbon monoxide: 2CO+O2 ignites 2CO2.
Other reactions:
36. Sodium carbonate reacts with dilute hydrochloric acid (the principle of fire extinguisher):
Na2CO3 + 2HCl == 2NaCl + H2O + CO2
Verb (abbreviation of verb) fuel and its utilization:
37. Methane burns in air: CH4+2O2 ignites CO2+2H2O.
38. Alcohol burns in the air: C2H5OH+3O2 ignites 2CO2+3H2O.
39. Burning in hydrogen and air: 2H2+O2 ignites 2H2O.
Six, metal
(1) the reaction of metal with oxygen;
40. Magnesium burns in air: 2Mg+O2 ignites 2MgO.
4 1. Iron burns in oxygen: 3Fe+2O2 ignites Fe3O4.
42. Copper is heated in air: 2Cu+O2 heats 2CuO.
43. Aluminum forms an oxide film in air: 4Al+3O2 = 2Al2O3.
(2) Simple metal+acid salt+hydrogen (displacement reaction)
44. Zinc and dilute sulfuric acid Zn+H2SO4 = ZnSO4+H2 Write
45. Iron and dilute sulfuric acid Fe+H2SO4 = FeSO4+H2 Write
46. Magnesium and dilute sulfuric acid Mg+H2SO4 = MgSO4+H2 Write
47. Aluminum and dilute sulfuric acid 2al+3H2SO4 = Al2 (SO4) 3+3H2 Write
48. Zinc and dilute hydrochloric acid Zn+2HCl = = ZnCl2+H2 Write
49. Iron and dilute hydrochloric acid Fe+2 HCl = = FeCl 2+H2 Write
50. Magnesium and dilute hydrochloric acid Mg Mg+ 2HCl == MgCl2+H2↑ =
5 1. aluminum and dilute hydrochloric acid 2Al+6HCl = = 2AlCl3+3H2 =
(3) Simple metal+salt (solution)-new metal+new salt
52. The reaction between iron and copper sulfate solution: Fe+CuSO4 == FeSO4+Cu.
53. The reaction between zinc and copper sulfate solution: Zn+CuSO4 ==ZnSO4+Cu.
54. The reaction between copper and mercury nitrate solution: Cu+Hg(NO3)2 == Cu(NO3)2+Hg.
(3) The refining principle of metallic iron:
55.3CO+ 2Fe2O3 high temperature 4Fe+3CO2↑ =
Seven, acid, alkali, salt
1, chemical properties of acid
(1) acid+metal salt+hydrogen (see above)
(2) Acid+metal oxide-salt+water
56. Reaction of iron oxide with dilute hydrochloric acid: Fe2O3+6HCl ==2FeCl3+3H2O.
57. The reaction of iron oxide with dilute sulfuric acid: Fe2O3+3H2SO4 == Fe2(SO4)3+3H2O.
58. The reaction of copper oxide with dilute hydrochloric acid: CuO+2HCl ==CuCl2+H2O.
59. The reaction between copper oxide and dilute sulfuric acid: CuO+H2SO4 == CuSO4+H2O.
(3) acid+alkali-salt+water (neutralization reaction)
60. Reaction between hydrochloric acid and caustic soda: HCl+NaOH == NaCl +H2O.
6 1. The reaction between hydrochloric acid and calcium hydroxide: 2HCl+Ca(OH)2 == CaCl2+2H2O.
62. Aluminum hydroxide drugs treat hyperacidity: 3HCl+Al(OH)3 == AlCl3+3H2O.
63. Reaction between sulfuric acid and caustic soda: H2SO4+2NaOH == Na2SO4+2H2O.
(4) acid+salt-another acid+another salt
64. marble reacts with dilute hydrochloric acid: CaCO3+2hcl = = CaCl2+H2O+CO2 =
65. Reaction of sodium carbonate with dilute hydrochloric acid: Na2CO3+2HCl = = 2NaCl+H2O+CO2 =
66. Sodium bicarbonate reacts with dilute hydrochloric acid: nahco3+HCl = = NaCl+H2O+CO2 =
67. The reaction between sulfuric acid and barium chloride solution: H2SO4+BaCl2 == BaSO4 ↓+ 2HCl.
2. Chemical properties of alkali
(1) alkali+nonmetallic oxide-salt+water
68. Caustic sodium will deteriorate when exposed to air: 2NaOH+CO2 == Na2CO3+H2O.
69. Caustic sodium absorbs sulfur dioxide gas: 2NaOH+SO2 == Na2SO3+H2O.
70. Caustic sodium absorbs sulfur trioxide gas: 2NaOH+SO3 == Na2SO4+H2O.
7 1. The slaked lime deteriorates in air: Ca(OH)2+CO2 == CaCO3 ↓+ H2O.
72. The slaked lime absorbs sulfur dioxide: Ca(OH)2+SO2 == CaSO3 ↓+ H2O.
(2) Alkali+acid-salt+water (neutralization reaction, see above).
(3) alkali+salt-another alkali+another salt
73. Calcium hydroxide and sodium carbonate: Ca(OH)2+Na2CO3 == CaCO3↓+ 2NaOH.
3. Chemical properties of salt
(1) salt (solution)+simple metal-another metal+another salt
74. The reaction between iron and copper sulfate solution: Fe+CuSO4 == FeSO4+Cu.
(2) salt+acid-another acid+another salt
75. Sodium carbonate reacts with dilute hydrochloric acid: Na2CO3+2HCl = = 2NaCl+H2O+CO2 =
Sodium bicarbonate reacts with dilute hydrochloric acid: nahco3+HCl = = NaCl+H2O+CO2 =
(3) salt+alkali-another alkali+another salt
76. Calcium hydroxide and sodium carbonate: Ca(OH)2+Na2CO3 == CaCO3↓+ 2NaOH.
(4) salt+salt-two new salts
77. Sodium chloride solution and silver nitrate solution: NaCl+AgNO3 == AgCl↓+NaNO3.
78. Sodium sulfate and barium chloride: Na2SO4+BaCl2 == BaSO4↓+2NaCl.
I. Scientific names, common names and chemical formulas of substances
(1) diamond, graphite: C (2) mercury, mercury: Hg (3) quicklime, calcium oxide: CaO(4) dry ice (solid carbon dioxide): CO2 (5) hydrochloric acid, hydrochloric acid: HCl(6) sulfurous acid: H2SO4 (7) bisulfate: H2S (8). 10H2O (1 1) sodium bicarbonate, acidic sodium carbonate: NaHCO3 (also called baking soda) (12) crystal of vitriol, blue vitriol and copper sulfate: CuSO4? 5H2O (13) verdigris, malachite: Cu2(OH)2CO3 (decomposed into three oxides) (14) methanol: CH3OH toxic, blinding, death (15) alcohol, ethanol: C2H5oh (/kloc-0). Acetic acid (16.6℃ glacial acetic acid) CH3COOH(CH3COO- acetate ion) has the commonality of acid (17) ammonia: NH3 (basic gas) (18) ammonia water and ammonia monohydrate: NH3? H2O (a common alkali with universality and no metal ions) (19) sodium nitrite: NaNO2 (industrial salt, toxic).
Second, the color 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 are purple-black.
3. Red solids: Cu, Fe2O3, HgO, red phosphorus ▲ Sulfur: pale yellow ▲ Cu2(OH)2CO3 is green.
4. Color of solution: Any solution containing Cu2+ is blue; Any solution containing Fe2+ is light green; Any solution containing Fe3+ is brown, and other solutions are generally not colorless. (Potassium permanganate solution is purplish red)
5. Precipitation (that is, salt and alkali are insoluble in water): ① Salt: white ↓:CaCO3, BaCO3 (soluble in acid), AgCl, BaSO4 (insoluble in dilute HNO3), etc. ② Alkali: blue: Cu (OH) 2 reddish brown: Fe (OH) 3 white: remaining alkali.
6.( 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: Liquid with pungent smell: hydrochloric acid, nitric acid and acetic acid. Alcohol is a liquid with a special gas.
7. Toxic, gas: CO liquid: CH3OH solid: NaNO2 CuSO4 (can be used as a 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 is insoluble in water, others are soluble in water.
Only BaSO4 is insoluble in water, others are soluble in water.
Only K2CO3, Na2CO3 and (NH4) CO32- 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 Fe(OH)2) Note: AgCl and BaSO4 in sediments are insoluble in dilute nitric acid.
Other precipitates can be dissolved in the acid. Such as: mg (oh) 2co3 baco3 ag2co3, etc.
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).
Fourth, the most in chemistry.
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. The simplest organic compound CH4
8. Under the same conditions, the gas with the lowest density is hydrogen. 9. The most conductive metal is silver.
10, and the atom with the smallest relative atomic mass is hydrogen. 1 1, and the metal with the smallest melting point is mercury.
12, the most abundant element in human body is oxygen. 13, the element that constitutes the most kinds of compounds is carbon.
14, the most widely used metal in daily life is iron. 15, China first used natural gas; The largest coal base in China is: Shanxi Province; The earliest application of copper hydrometallurgy was China (discovered in the Western Han Dynasty [Liu An's "Huainan Wanbi Book" Zeng Qing De Tiehua Copper]] and applied in the Song Dynasty); The earliest discovery of electrons was Thomson of England; Lavoisier, a Frenchman, first came to the conclusion that air is composed of N2 and oxygen.
Five, the "three" in junior high school chemistry
1. The three kinds of particles that make up matter are molecules, atoms and ions.
2. Hydrogen, carbon monoxide and carbon, which are usually used to reduce copper oxide.
3. As a fuel, hydrogen has three advantages: rich resources and high calorific value, and the product after combustion is water that does not pollute the environment. There are generally three kinds of particles that make up atoms: protons, neutrons and electrons. There are only three kinds of ferrous metals: iron, manganese and chromium. 6. Elements that make up a substance can be divided into three categories, namely (1) metallic elements, (2) nonmetallic elements and (3) rare gas elements. 7. There are three kinds of iron oxides, and their chemical formulas are (1)FeO, (2)Fe2O3 and (3) Fe3O4.
8. The characteristic of the solution is three (1) homogeneous; (2) stability; (3) mixture.
9. The chemical equation has three meanings: (1) indicates what substances participate in the reaction and what substances are generated as a result; (2) The particle number ratio of molecules or atoms between reactants and products; (3) Represents the mass ratio of each reactant and product. Chemical equations have two principles: based on objective facts; Follow the law of conservation of mass. 10 pig iron is generally divided into white iron, gray iron and ductile iron.
Carbon steel can be divided into three types: high carbon steel, medium carbon steel and low carbon steel.
12. There are three kinds of iron ore commonly used in ironmaking: (1) hematite (mainly Fe2O3); (2) Magnetite (Fe3O4); (3) siderite (FeCO3). There are mainly three kinds of steelmaking equipment: converter, electric furnace and open hearth furnace.
14. The three reaction conditions that are often related to temperature are ignition, heating and high temperature.
15. There are two ways to change saturated solution into unsaturated solution: (1) heating, (2) adding solvent; There are three methods to change unsaturated solution into saturated solution: cooling, adding solute and evaporating solvent at constant temperature. (Note: For substances whose solubility decreases with temperature, such as calcium hydroxide solution changes from saturated solution to unsaturated solution: cool and add solvent; There are three ways to change unsaturated solution into saturated solution: raising temperature, adding solute and evaporating solvent at constant temperature.
16. There are generally three methods to collect gas: drainage, upward evacuation and downward evacuation.
17, three main causes of water pollution: (1) waste residue, waste gas and waste water in industrial production; (2) Discharging domestic sewage at will; (3) Pesticides and fertilizers used in agricultural production flow into rivers with rainwater.
18, there are three commonly used fire extinguishers: foam extinguisher; Dry powder fire extinguisher; Liquid carbon dioxide fire extinguisher.
19. The change of solubility of solid substances with temperature can be divided into three categories: (1) The solubility of most solid substances increases with the increase of temperature; (2) The solubility of a few substances is little affected by temperature; (3) The solubility of a few substances decreases with the increase of temperature. 20.CO2 can put out fires for three reasons: it can't burn, it can't help combustion, and its density is higher than that of air. 2 1, simple substances can be divided into three categories: metallic simple substances; Non-metallic simple substance; Simple substance of rare gas. 22. The three most important fossil fuels in the world today are coal, oil and natural gas.
23. The three black oxides that should be remembered are copper oxide, manganese dioxide and ferroferric oxide.
24. Hydrogen and carbon have three similar chemical properties: stability at room temperature, flammability and reducibility.
25. There are three times of light blue in the textbook: (1) liquid oxygen is light blue (2) sulfur burns in the air with a weak light blue flame (3) hydrogen burns in the air with a light blue flame.
26. Three blue colors related to copper: (1) copper sulfate crystal; (2) copper hydroxide precipitation; (3) copper sulfate solution. 27. The filtration operation has "triple inclination": (1) The lower end of the funnel is close to the inner wall of the beaker; (2) the end of the glass rod gently leans against the third layer of filter paper; (3) The edge of the beaker containing the liquid to be filtered is close to the glass frame for drainage.
28. Three major gas pollutants: SO2, CO and NO2.
29. The flame of alcohol lamp is divided into three parts: external flame, internal flame and flame core, of which the external flame has the highest temperature.
30. There are three noes in taking and using drugs: (1) Don't touch drugs with your hands; (2) Don't put your nose to the mouth of the container to smell the smell of gas; (3) Do not taste medicine. 3 1. Three ancient chemical processes: papermaking, gunpowder making and porcelain burning. Industrial three wastes: waste water, waste residue and waste gas.
34. Three kinds of instruments that can be directly heated: test tube, crucible, evaporating dish (and burning spoon).
35. The three atoms explained by the conservation of mass remain the same: the species remains the same, the quantity remains the same, and the mass remains the same.
36. Mixing with air ignites three potentially explosive gases: H2, carbon monoxide and methane (virtually any combustible gas and dust). 37. Three products of coal dry distillation (chemical change): coke, coal tar and coke oven gas.
38. Three characteristics of concentrated sulfuric acid: water absorption, dehydration and strong oxidation.
39. There are three prohibitions on the use of alcohol lamps: burning lamps, burning lamps with alcohol, and blowing mouths.
40. Three steps of solution preparation: calculation, weighing (measurement) and dissolution.
4 1, the first three elements with the most content in biological cells: O, C and H.
42. Three equations in atoms: nuclear charge number = proton number = extranuclear electron number = atomic number.
There are three kinds of particles that make up matter: molecules, atoms and ions.
Chemical formula
1, basic reaction type:
Combinatorial reaction: multivariable-decomposition reaction: multivariable
Displacement reaction: one-to-one displacement reaction: exchange ions
2. Valence of common elements (positive):
Univalent potassium, sodium, hydrogen, silver, bivalent calcium, magnesium, barium and zinc, trivalent metal element aluminum;
157 variable valence chlorine, 245 nitrogen, 46 sulfur, 35 phosphorus, 24 carbon;
One, two copper, two, three iron and two, four, six and seven manganese are special.
3, the steps of making oxygen in the laboratory:
"Tea (stop), tea (bag), tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea, tea,
Check the air tightness of the equipment "package" the medicine and connect the equipment.
The "fixed" test tube is fixed on the "point" of the iron frame, and the alcohol lamp is lit and heated.
"Collect" the collected gas and "leave" the conduit away from the water surface.
Turn off the alcohol lamp and stop heating.
4. Experimental steps of reducing copper oxide with CO:
"One pass, two points, three extinctions, four stops and five treatments"
"One pass" is filled with hydrogen first, and after "two points", the alcohol lamp is lit for heating;
After the "three-stop" experiment is completed, the alcohol lamp should be turned off first, and then the hydrogen gas should be stopped at room temperature after the "four stops". "Five treatments" to control tail gas and prevent carbon monoxide from polluting the environment.
5, the experimental phenomenon of electrolytic water:
"oxygen positive hydrogen negative, oxygen one hydrogen two": the positive electrode releases oxygen and the negative electrode releases hydrogen; The volume ratio of oxygen to hydrogen is 1: 2.
6. Elements that make up the earth's crust: adopted sons (oxygen, silicon, aluminum).
7. Relationship between outermost atoms and ions and valence formation:
"Yang loss is positive, Yin gain is negative, and the value remains unchanged": the outermost layer of atoms loses electrons to form cations, and the valence of elements is positive; The outermost layer of atoms gains electrons to form anions, and the valence of elements is negative; Number of electrons gained or lost = number of charges = valence.
8, chemical experiment basic operation formula:
Solids need spoons or paper slots, one free, two vertical and three elastic; It is best to use a block or tweezers, one horizontal and two vertical.
The liquid should be put in a flask, labeled by hand, and then poured out. The reading should be flat with the section, with the head down low and the head down high.
The dropper drips with a pinch head, and the vertical suspension is pollution-free, uneven and in good position. Don't forget to clean it after use.
The balance of the tray should be flat and the screw should be centered; Put things left and right, and clamp the tweezers first big and then small;
The test paper should be cut down first, and the glass rod is immersed in liquid for the best test effect. Wet the test paper first, stick it on a stick and lean against the air.
The outer flame of the heating wine lamp is two-thirds of the boundary. Sulfuric acid is stirred in water and injected slowly to prevent boiling and splashing.
In the experiment, the air tightness is checked first, and the cups and bottles are heated through the net. After drainage and gas collection, remove the conduit first, and then move the lamp.
9, metal activity sequence:
The order of metal activity from strong to weak is: K Ca Na Mg Al Zn Fe Sn Pb (H) Cu Hg Ag Pt Au (described in turn) K Ca Na Mg Al Zn Fe Sn Pb (hydrogen) Cu Hg Ag Pt Au.
10, "cross method" to write the formula of chemical formula:
"Positive price left negative price right, cross subtraction, write right to test right and wrong."
1 1, filtering operation formula:
The funnel angle of the glass rod and filter paper of the beaker of the bucket frame is the same; Let stand before filtering, don't forget to tilt three times and two times.
12, the law in the experiment:
(1) When solid is heated to produce gas, potassium permanganate oxygen generator (solid-solid heating type) is selected;
The device for preparing O2 from hydrogen peroxide (solid-liquid unheated type) is used to prepare gas by solid-liquid reaction without heating.
(2) When heating the test tube solid, it should be preheated first, and the test tube mouth is slightly inclined downward.
(3) Any generated gas that is insoluble in water (does not react with water) can be collected by drainage.
Any gas with higher density than air can be collected by exhausting upwards.
Any gas less dense than air can be collected by downward exhaust.
(4) When doing the gas experiment, first check the air tightness of the device, the rubber plug 1-2ml should be exposed on the catheter, and the iron clip should be clamped at the distance from the nozzle 1/3.
⑤ When making gas with a long-necked funnel, the nozzle at the end of the long-necked funnel should be inserted under the liquid surface.
⑥ When igniting combustible gas, you must first check its purity.
⑦ When doing experiments with toxic gases, the tail gas must be finally treated.
⑧ When reducing metal oxides with reducing gas, "one pass, two points, three extinguishes and four stops" must be achieved.
13, reaction law: displacement reaction:
(1) Elemental metal+acid → salt+hydrogen
(2) simple metal+salt (solution) → another metal+another salt
(3) metal oxide+charcoal or hydrogen → metal+carbon dioxide or water
Double decomposition reaction:
① Alkaline oxide+acid → salt ++H2O ② Alkali+acid → salt +H2O
③ Acid+salt → new salt+new acid ④ salt 1+ salt 2→ new salt 1+ new salt 2.
⑤ salt+alkali → new salt+new alkali
14, metal+acid → salt+++H2↑ =
(1) metal reacts with enough acid to release hydrogen in the order of Al > Mg > Fe > Zn.
② Different acids with equal mass react with enough metals, and the smaller the relative molecular weight of the acid, the more hydrogen is released.
③ The same acid with the same mass reacts with enough different metals to release the same amount of hydrogen.
(4) After the reaction of metal+acid → salt +H2 ↑, the solution becomes heavier and the metal becomes lighter.
Metal+salt solution → new metal+new salt:
① When the relative atomic mass of the metal is greater than that of the new metal, the mass of the solution becomes heavier and the metal becomes lighter after the reaction.
② When the relative atomic mass of the metal is less than that of the new metal, the mass of the solution becomes lighter and the metal becomes heavier after the reaction.
15, catalyst: one change and two unchanged (a substance whose chemical properties and quality are unchanged by changing the reaction rate of a substance is a catalyst).
Oxidant and reductant: oxygen is reduced and deprived (the substance that takes oxygen is reductant, and the substance that loses oxygen is oxidant).
16. Impurity removal connector of gas washing cylinder: long inlet and short outlet.
Connection between drainage and gas collection and washing tank: short in and long out.
Connection between exhaust gas gathering and gas washing cylinder: low density means short inlet and outlet, while high density means long inlet and outlet.
17, experimental impurity removal principle: remove other things first, and then remove water vapor.
Experimental inspection principle: water first, then water.