Common name chemical formula
Diamond, graphite carbon
Ethanol ethanol C2H5OH
Hydrated lime calcium hydroxide Ca(OH)2
Quicklime, calcium oxide and calcium oxide
Acetic acid (melting point 16.6℃, solid is called glacial acetic acid) acetic acid CH3COOH.
Lignol methanol CH3OH
Dry ice solid carbon dioxide carbon dioxide
Copper (Ⅱ) (OH) 2co3 Basic Carbonate of Chlorophyll and Malachite
Copper sulfate crystal sulfuric acid and blue vitriol copper sulfate
H2S bisulfate
hydrosulfite
Saline (industrial name) hydrochloric acid
Mercury mercury
Soda, soda, sodium carbonate Na2CO3.
Sodium carbonate crystal Na2CO3 10H2O
Acid sodium carbonate, baking soda, sodium bicarbonate NaHCO3
Caustic soda, caustic soda, caustic soda, sodium hydroxide, sodium hydroxide
Toxic nitrate (industrial name) sodium nitrite
Ammonia H2O monohydrate
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 solids: copper, iron oxide, mercury oxide and 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 (insoluble in dilute HNO3), etc. ② 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: CO liquid: CH3OH solid: NaNO2, CuSO4 (can be used as bactericide, mixed with hydrated lime to make 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.
Only BaSO4 and PbSO4 are insoluble in water, AgSO4 is slightly soluble in water, and 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 iron hydroxide)
Note: AgCl and BaSO4 in sediments are insoluble in dilute nitric acid, while other sediments are soluble in acid. Such as: mg (oh) 2co3 baco3.
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, 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.
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, China was the first to use wet copper smelting (discovered in the Western Han Dynasty [Liu An's Huainan Wanbi Shu "Zeng Qing De Tiehua Copper"] and applied in the Song Dynasty);
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, mercury is liquid), and nonmetals are not always gas or solid (for example, Br2 is liquid). Note: Metals and nonmetals refer to simple materials and should not be confused with material composition.
3. Atomic groups must be charged ions, but not necessarily acidic groups (such as NH4+, OH-); ; Acids are not necessarily atomic groups (for example, Cl- is 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 mononuclear particles (one atom and one nucleus) with the same nuclear charge 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 will inevitably change in the redox reaction.)
14, simple substance must not be decomposed.
15, the same element does not necessarily show a valence in the same compound. For example, 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. Such as H+ and 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 can contain metallic elements (for example, HMnO4 is called permanganate), but all material components must contain nonmetallic elements.
19, the salt solution is not necessarily neutral. For example, Na2CO3 solution is alkaline.
20, acidic salt solution 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 acidic solution must be acidic, but it is not necessarily acidic. For example, H2SO4 and NaHSO4 are both acidic, and NaHSO4 is a 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. For example, NaOH, Na2CO3 and NaHCO3 solutions are all alkaline, while Na2CO3 and NaHCO3 are salts. 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 its 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. Acidic oxides are not necessarily nonmetallic oxides (such as Mn2O7), and nonmetallic oxides are not necessarily acidic oxides (such as H2O, CO and NO). ★ Common acidic oxides: CO2, SO2, SO3, P2O5, SiO2, etc. Most acidic oxides can be dissolved in water and react with water to generate corresponding acids. Remember that silicon dioxide (SiO2) is 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. If Na is added to CuSO4 solution, the reaction will be: 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. Before ignition or heating, be sure to check the purity of combustible gas.
33. When writing a chemical formula, all positive valence elements are not necessarily written on the left. Such as NH3 and 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%.
Can be equal to 5%, such as NaCl, KNO3, etc. It can also be greater than 5%, such as, Na2O, BaO, etc. It may also be less than 5%, such as crystalline hydrate and Ca(OH)2, CaO, etc.
◆ Under the same conditions, CaO or Ca(OH)2 is dissolved in water to obtain the smallest solute mass fraction.
Sixth, the "three" in junior middle 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.
16. There are generally three methods to collect gas: drainage method, upward ventilation method and downward ventilation method.
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 manufacturing and porcelain firing.
32. Industrial three wastes: waste water, waste residue and waste gas.
33. Three kinds of instruments that can be directly heated: test tube, crucible, evaporating dish (and burning spoon).
34. The three atoms explained by the conservation of mass are unchanged: the species is unchanged, the quantity is unchanged, and the mass is unchanged.
35. Mixing with air ignites three potentially explosive gases: H2, carbon monoxide and methane (virtually any combustible gas and dust).
36. Three main products of coal dry distillation (chemical change): coke, coal tar and coke oven gas.
37. Three characteristics of concentrated sulfuric acid: water absorption, dehydration and strong oxidation.
38. Three prohibitions on alcohol lamps: light, add alcohol to the lit lamp, and blow your mouth.
39. Three steps of solution preparation: calculation, weighing (measurement) and dissolution.
40. The first three elements with the most content in biological cells: O, C and H.
Three equations in 4 1. atom: nuclear charge number = proton number = extranuclear electron number = atomic number.
Seven, metal activity sequence:
The order of metal activity from strong to weak is potassium, calcium, sodium, magnesium, aluminum, zinc, iron, tin, lead (hydrogen), copper, mercury, silver and platinum.
Potassium, calcium, sodium, magnesium, aluminum, zinc, iron, tin, lead (hydrogen), copper, mercury, silver and platinum.
A formula of metal fluidity order: Jiamei donkey, whose new hoof likes to pull lightly, weighs 100 Jin.
Meaning: There is a beautiful donkey named Jia Gai who likes to carry (pull) light goods with new hooves. According to statistics, it's only 100 Jin.
① The higher the metal position, the stronger the activity, the easier it is to lose electrons and become ions, and the faster the reaction speed.
(2) The metal in front of hydrogen can replace the hydrogen in acid, while the metal behind hydrogen cannot replace the hydrogen in acid and does not react with acid;
(3) The former metals can replace the latter metals from their salt solutions. The latter metal does not react with the salt solution of the former metal.
④ The order of displacement reaction between mixed salt solution and metal is "first far, then near"
Note: * In the displacement reaction, elemental iron always becomes ferrous with valence +2.
Eight, metal+acid → salt+++H2↑ =
(1) When the metal with the same mass reacts with enough acid, the order of hydrogen evolution is 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.
3. Material inspection
(1) acid (H+) test.
Methods 1 purple litmus test solution was dropped into a test tube containing a small amount of liquid to be tested and shaken evenly. If litmus test solution turns red, it proves the existence of H+.
Method 2: Immerse a drop of unknown liquid into blue litmus test paper with a dry and clean glass rod. If the blue test paper turns red, it proves the existence of H+.
Method 3: Dip an unknown liquid drop into the pH test paper with a dry and clean glass rod, and then compare the color displayed on the test paper with the standard colorimetric card to know the pH value of the solution. If the pH is less than 7, the existence of H+ is proved.
(2) Silver salt (Ag+) test.
Pour a small amount of hydrochloric acid or a small amount of soluble hydrochloric acid solution into a test tube containing a small amount of liquid to be detected, and shake. If white precipitate occurs, add a small amount of dilute nitric acid. If the precipitate does not disappear, it proves the existence of Ag+.
(3) Check the alkali (OH-).
Methods 1 purple litmus test solution was dropped into a test tube containing a small amount of liquid to be tested and shaken evenly. If litmus test solution turns blue, it proves the existence of OH-.
Method 2: Immerse a drop of unknown liquid in red litmus test paper with a dry and clean glass rod. If the red litmus test paper turns blue, it proves the existence of OH-.
Method 3 Drop colorless phenolphthalein test solution into a test tube containing a small amount of liquid to be tested and shake well. If the phenolphthalein test solution turns red, it proves the existence of OH-.
Method 4 Dip an unknown liquid drop into the pH test paper with a dry and clean glass rod, and then compare the color displayed on the test paper with the standard colorimetric card to know the pH value of the solution. If the pH is greater than 7, it proves the existence of OH-.
(4) Inspection of chloride or hydrochloride or hydrochloric acid (Cl-).
Pour a small amount of silver nitrate solution into a test tube filled with a small amount of liquid to be measured and oscillate. If white precipitate occurs, add a small amount of dilute nitric acid. If the precipitate does not disappear, it proves the existence of Cl-.
(5) Inspection of sulfate or sulfuric acid (SO42-).
Pour a small amount of barium chloride solution or barium nitrate solution into a test tube filled with a small amount of liquid to be detected and oscillate. If white precipitate occurs, add a small amount of dilute nitric acid. If the precipitate does not disappear, it proves the existence of SO42-.
(6) Detection of CO32-or HCO3-.
Pour a small amount of hydrochloric acid or nitric acid into a test tube containing a small amount of substances to be detected. If a colorless gas is released, introduce the gas into a test tube containing a small amount of clear limewater. If the limewater becomes turbid, it proves that there is CO32- or HCO3 in the original substance to be detected.
* SO42- and Cl- coexist. If we want to test, we must first remove SO42- with Ba(NO3)2 solution and then test Cl- with AgNO3 solution, because if AgSO4 generated by the reaction between AgNO3 and SO42- is slightly soluble, it is not clear whether it is Cl- or SO42-. Ba(NO3)2 must be used here, and if BaCl2 is used, Cl- is introduced.
(6) Ammonium salt (NH4+):
Using concentrated sodium hydroxide solution (slightly hot) to generate gas, the wet red litmus paper turns blue.
Nine, 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.
(3) After the reaction of metal+acid → salt+H2 =, the solution becomes heavier and the metal becomes lighter.
X. factors affecting the combustion of substances:
(1) Different oxygen concentrations make different products. For example, carbon produces carbon dioxide when oxygen is abundant and carbon monoxide when oxygen is insufficient.
② Different oxygen concentrations have different phenomena. For example, sulfur is a light blue flame in air and a blue flame in pure oxygen.
③ Different oxygen concentrations have different reaction degrees. For example, iron can burn in pure oxygen, but not in air.
(4) Different contact areas of substances have different combustion degrees. Such as the burning of briquettes and honeycomb briquettes.
XI。 Factors affecting the dissolution of substances:
① Stir or oscillate. Stirring or shaking can accelerate the dissolution of substances.
2 heat. Temperature rise can accelerate the dissolution of substances.
③ Solvent. Different substances have different solubility in the selected solvents.
Twelve, the law of the periodic table of elements:
① The number of electron layers of the same periodic element is the same. From left to right, the number of nuclear charges, protons and extranuclear electrons increases.
② The same group of elements have the same number of extranuclear electrons and similar chemical properties, and the number of nuclear charges, protons and electron layers increase from top to bottom.
Thirteen, eight decisive relations in the knowledge of atomic structure:
The number of protons determines the number of charges (nuclear charges) carried by the nucleus.
Because the number of protons in an atom = the number of nuclear charges.
② The number of protons determines the types of elements.
The number of protons and neutrons determines the relative atomic mass of atoms.
Because the number of protons+neutrons of an atom = the relative atomic mass of an atom.
④ The level of electron energy determines the distance between the electron movement region and the nucleus.
Because the closer an electron is to the nucleus, the lower its energy, and the farther it is from the nucleus, the higher its energy.
⑤ The number of electrons in the outermost layer of atoms determines the category of elements.
Because the number of electrons in the outermost layer of an atom < 4 is metal, > or = 4 is nonmetal, and = 8 (when the first layer is the outermost layer = 2) is a rare gas element.
⑥ The number of electrons in the outermost layer of atoms determines the chemical properties of elements. Because the number of electrons in the outermost layer of an atom < 4 is electron loss, > or = 4 is electron gain, and = 8 (when the first layer is the outermost layer = 2) is stable.
⑦ The number of electrons in the outermost layer of atoms determines the valence of elements.
After the atom loses electrons, the element presents a positive valence, and after gaining electrons, the element presents a negative valence, and valence state = the number of electrons gained and lost.
The number of electrons in the outermost layer of an atom determines the number of charges carried by ions.
Atoms are cations after losing electrons, and anions after gaining electrons. Charge number = number of electrons gained and lost.
Fourteen, junior high school chemistry experiment "first" and "after"
① Use pallet balance: when using pallet to level, first adjust the balance. When adjusting the balance, first move the wandering code to zero scale, and then turn the balance nut to achieve balance.
② Heating: When the medicine is heated in a test tube or flask, it should be preheated first and then heated centrally.
③ Gas preparation: When preparing gas, the air tightness of the device must be checked before charging.
④ Solid-liquid mixing: When solid and liquid are mixed or react with each other, the solid should be added first, and then the liquid should be added.
⑤ Detection of combustible gas: When detecting the flammability of hydrogen and other gases, the purity of hydrogen and other gases should be detected first, and then the flammability and other properties should be detected.
⑥ Redox reaction: When reducing copper oxide and other solid substances with reducing gases (such as H2 and CO), heating is generally required. In the experiment, a period of gas should be introduced before heating. After the experiment, continue to introduce hydrogen, first remove the alcohol lamp until the test tube cools, and then remove the airway.
⑦ Diluting concentrated sulfuric acid: When diluting concentrated sulfuric acid, first add distilled water into the beaker, then slowly inject concentrated sulfuric acid along the wall of the beaker, constantly stir with a glass rod, cool and bottle.
(8) Separating the mixture: separating the mixture of salt and potassium nitrate by recrystallization. When the salt accounts for a considerable amount, the saturated solution can be heated and evaporated to separate out salt crystals, filtered, and then the mother liquor is cooled to separate out potassium nitrate crystals; When potassium nitrate accounts for a considerable amount, the hot saturated solution can be cooled to separate out potassium nitrate crystals, then filtered, and then the mother liquor can be evaporated to separate out salt crystals.
Pet-name ruby neutralization titration: In neutralization titration experiment, the solution to be tested is generally an alkaline solution. First, add phenolphthalein reagent to the solution to be tested to make it appear red, then add acid solution drop by drop and stir until the red color just recedes.
⑩ Removing carbon dioxide and water vapor from the mixed gas: When removing carbon dioxide and water vapor from the mixed gas, the mixed gas should first pass through the washing tank filled with concentrated sodium hydroxide solution and then through the washing tank filled with concentrated sulfuric acid.
⑿ Check whether the mixed gas is mixed with carbon dioxide and water vapor: When checking whether the mixed gas is mixed with carbon dioxide and water vapor, it should first pass through a drying tube filled with anhydrous copper sulfate and then through a washing cylinder filled with limewater.
[13] Testing acid gas or alkaline gas: When testing hydrogen chloride gas, first wet the blue litmus test paper with distilled water, and then test it with test paper to make it turn red; When measuring ammonia, first soak the red litmus test paper with distilled water, and then test it with test paper to make it blue.
14. displacement reaction between metal and salt solution: the sequence of displacement reaction between mixed solution and a metal is "first far, then near"; The displacement reaction sequence of metal mixture and salt solution is also "far first and then near" If Al and Mg react with FeCl3 _ 3 solution at the same time, the distance between Mg and Fe is far, and the distance between Al and Fe is close (the order in the metal activity sequence table).
Fifteen, some laws in the reaction:
① SO42- must react with Ba2+ to form a white precipitate insoluble in dilute HNO3, which is BaSO4.
② Cl- must react with Ag+ to form a white precipitate insoluble in dilute HNO3, which is AgCl.
③ CO32- (or HCO3- ion, but generally not considered) must react with hydrochloric acid to generate gas that can clarify the turbidity of limewater * All carbonates can react with acid to generate CO2 gas.
④ The gas (NH3) that can make wet red litmus test paper react with alkali and turn into blue must be NH4+ (i.e. ammonium salt).
* Only NH3 (NH3(NH3+H2O = NH3·H2O) is an alkaline gas dissolved in water.
⑤SO42- and Cl- exist at the same time. If we want to test, we must first test and remove SO42- with Ba(NO3)2 solution, and then test Cl- with AgNO3 solution.
⑥ Soluble alkali cannot be decomposed by heating, but only insoluble alkali can be decomposed by heating. Copper hydroxide △ copper oxide +H2O.
⑦ Soluble carbonate cannot be decomposed by heating, but only insoluble carbonate can be decomposed by heating. CaCO3=CaO+CO2↑ (acid carbonate is unstable and easy to decompose when heated: 2NaHCO3=Na2CO3+H2O+CO2↑).
Sixteen, 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.
Seventeen, the data in the basic operation of the experiment:
1, use a funnel to add alcohol to the alcohol lamp, but the amount of alcohol should not exceed the volume of the lamp body. When the liquid is heated in a test tube, it shall not be less than.
2. When the liquid vibrates in the test tube, the volume of the liquid shall not exceed the volume of the test tube.
3. When heating the liquid with a test tube, it should also be noted that the volume of the liquid cannot exceed the volume of the test tube. When heating, the test tube should be tilted about 45 degrees from the desktop.
4. When heating the solid in the test tube, the iron clip should be clamped at a certain distance from the nozzle.
4. The pallet balance can only be used for rough weighing and can be calibrated to 0.1g..
5. If the acidic solution accidentally touches the skin or clothes, immediately rinse it with more water (if it is concentrated sulfuric acid, it must be quickly wiped with a rag and then rinsed with water), and then rinse it with sodium bicarbonate solution with solute mass fraction of 3∽5%.
6. Take medicine during the experiment. If there is no prescribed dose, generally take it according to the minimum amount: 1 ∽ 2ml of liquid, just cover the bottom of the test tube with solid.
7. When using the test tube clamp, it should be inserted upward from the bottom of the test tube and fixed away from the test tube mouth.