Recommended glue: for domestic use, the surface material to be bonded is black plastic, which is hard (too brittle with AB glue) and ...

Magnesium burns in air: 2MG+O2 ignites 2MgO phenomenon: (1) A dazzling white light (2) releases heat (3) produces white powder.

2. Iron burns in oxygen: 3FE+2O2 ignites ferroferric oxide.

Phenomena: (1) Heat of intense combustion (3) Sparks (2) Black solids are produced.

Note: put a small amount of water or sand in the bottle at the bottom to prevent the generated solid matter from splashing out and exploding the bottom of the bottle.

4. The heat of copper in air: 2CU+O2△2CuO phenomenon: copper black.

6. Aluminum burns in air: 4AL+3O2 ignites 2Al2O3.

Phenomenon: The dazzling white light reacts exothermically to form a white solid.

7. Hydrogen burns in air: 2H2+O2 ignites 2H2O.

Phenomenon: (1) light blue flame (2)(3) beaker fog in heat release.

8. Red (white) phosphorus burns in air: 4P+5O2 ignites 2P2O5.

Phenomenon: (1) White light (2) releases heat (3) produces a lot of white smoke.

9. Sulfur powder burns in air: S+O2 ignites SO2 phenomenon: pure oxygen.

Give off bright blue-purple flame, give off heat, and produce gas with pungent smell.

Burning air

(1) Releases heat (3) Gases with pungent odor emit light blue flames (2).

10, carbon fully burns in oxygen: C+O2 ignites CO2.

Phenomena: (1) White light (2) Exothermic (3) Clear lime water on cloudy days.

1 1 Combustion under insufficient carbon and oxygen supply: 2C+O2 ignites 2CO.

12 carbon dioxide passes through the burning carbon layer: C+CO2 at high temperature (endothermic reaction)

13, carbon monoxide burns in oxygen: 2CO+O2 ignites 2CO2.

Phenomenon: blue flame is released, heat is released, and lime water is clarified on cloudy days.

14, carbon dioxide reacts with water (carbon dioxide is introduced into purple litmus solution):

CO2+H2O === H2CO3 phenomenon: litmus test solution turns from purple to red.

Note: Acid oxide+water → acid.

For example, SO2+H2O = = H2SO4, SO3+H2O = = = H2SO4.

15 Cao+H2O = = Ca (OH) 2 (exothermic) lime is soluble in water.

Note: Alkaline oxide+water → Alkaline

Sodium oxide is easily soluble in water. Sodium oxide +H2O = 2NaOH.

Hydroxide is soluble in water: K2O+H2O = 2KOH.

Barium oxide is soluble in water: Bao+H2O = = Ba (OH) 2.

16, Combustion of Sodium in Chlorine: Ignition of Disodium +Cl2 2NaCl

17 anhydrous desiccant copper sulfate: copper sulfate +5h2o = = = copper sulfate 5h2o.

Second, the decomposition reaction:

17, the function of water is DC decomposition: 2H2O charged 2H2↑+ O2↑ =

> phenomenon: (1) bubbles are formed at the electrode. H2: oxygen = 2: 1

The gas produced by the cathode can be revived with wood from Mars.

Negative gas burns in the air, giving off a light blue flame.

18 is the heating of basic copper carbonate: Cu2 (OH) 2co3 △ 2cuo+H2O+CO2 =

Phenomenon: the blue-black pipe wall condenses into powder, clear and turbid lime water.

19, heating potassium chlorate (with a small amount of manganese dioxide):: 2kCl 2kcl3omno2+3o2 =

20 heating potassium permanganate: 2k MnO 4△k2mno 4+ manganese dioxide+O2 =

2 1, laboratory oxygen and hydrogen peroxide system: 2H2O 22 manganese dioxide 2H2O+O2↑ =

Phenomenon: 60-75, resurgence with Martian wood.

22. Heating mercury oxide: 2hg02hg+O2 =

23 Calcined limestone: CaCO3+CO2↑ = calcium (legal carbon dioxide system)

24. Carbonic acid is unstable and decomposed: H2CO3 === H2O+CO2↑ =

Phenomenon: litmus test solution changes from red to purple.

25. Thermal decomposition of copper sulfate crystal: copper sulfate 5h2o heats copper sulfate +5H2O.

Displacement reaction:

(1) Simple metal+acid salt+hydrogen (displacement reaction)

26. Reaction of zinc with dilute sulfuric acid: zinc +H2↑SO4 === zinc sulfate +H2 =

27. Reaction of magnesium with dilute sulfuric acid: magnesium +H2↑SO4 === magnesium sulfate +H2 =

28. Reaction of aluminum with dilute sulfuric acid: Except 2A1+3H2SO4 = = Al2 (SO4) 3+3H2 =

29. Reaction of zinc with dilute hydrochloric acid: zinc+2hcl = = zinc chloride+H2 =

30. Reaction of magnesium with dilute hydrochloric acid: magnesium +2HCl = = magnesium chloride+H2 =

3 1, the reaction of aluminum with dilute hydrochloric acid: 2al+6hcl = = 2alcl3+3h2 =

The phenomenon of 26-3 1: bubbles.

32. Reaction of iron with dilute hydrochloric acid: iron +2HCl = = ferrous chloride+H2 =

33. Reaction of iron with sulfuric acid: iron+H2 = SO4 = =+H2 of ferrous sulfate =

32-33 phenomenon caused bubbles from colorless to light green solution.

(2) Simple metal+salt (solution)-another metal+and other salts.

36. Reaction between iron and copper sulfate: iron+= = copper sulfate+ferrous sulfate.

Phenomenon: the surface of the iron bar is covered with a layer of red substance, and the solution changes from blue to bright green.

(The ancient copper mine wet process and "Zeng 72 is iron and copper" refer to this reaction)

Put 40% zinc sheet into copper sulfate solution: copper sulfate+=, zinc sulfate+copper sulfate BR/> Phenomenon: the surface of zinc sheet is covered with red substance, and the solution turns blue and colorless.

4 1, silver nitrate copper solution: 2AgNO3+Cu(NO3)2 +2 silver and copper = =

Phenomenon: The copper surface is covered with a layer of silver white material, and the solution turns from colorless to blue.

(3) metal oxide+charcoal or hydrogen → metal+carbon dioxide or water

38 Iron oxide reduced by coke: 3C+2Fe2O3, high temperature, 4FE+3CO2↑ =

39. Copper oxidation by charcoal reduction: C+2CU 0, high temperature 2CU+CO2↑ =

Phenomenon: black powder turns red, and lime water is clarified on cloudy days.

25. Reduction of copper oxide by hydrogen: H2+CuO △ copper +H2O.

Phenomenon: the black powder turns red and the pipe wall descends.

34. Reaction of magnesium and copper oxide: magnesium+copper oxide +MgO content.

35. Iron hydroxide Fe2O3 +3 H2 2FE +3 H2O

Reaction of burning carbon layer with water vapor: H2+CO+C, high temperature H2+Co.

Fourthly, the metathesis reaction:

1, basic oxide+acid → salt +H2O

Fe2(SO4)3 +3 H2O and ferric oxide +6 hydrochloric acid = = 2fecl3 +3 H2SO4 ==

Copper oxide+sulfuric acid = copper sulfate+zinc oxide H2O+nitric acid = zinc nitrate +H2O.

2. Alkali+acid → salt +H2O

Study on Cu (OH) 2+2HCl = = CuCl2+2H2O Cu (OH) 2+H2SO4 = = CuSO4+2H2O

Sodium hydroxide+hydrochloric acid = = salt +H2O 2NaOH+H2SO4 == sodium sulfate +2 H2O.

Sodium hydroxide+nitric acid = = sodium nitrate+magnesium H2O (OH )2 +2 nitric acid = = magnesium nitrate +H2O

Ba(OH)2+H2SO4 == barium sulfate ↓+2 H2O

3. Acid+salt → salt+new acid

Hydrochloric acid+silver nitrate == AgCl electrode ↓+HNO 3 h2so 4+ barium chloride = = barium sulfate ↓+2 hydrochloric acid br/>; Ba(NO3)2+H2SO4 == barium sulfate ↓+2 HNO3 sodium bicarbonate+hydrochloric acid = = sodium chloride+H2O+CO2 =

4. Salt 1+ new salt 2→ 1+ new salt

AgNO3+of & gtKCl = KNO3+of AgCl electrode NaCl = = AgCl electrode↓+sodium nitrate.

Sodium sulfate+barium chloride = = barium sulfate ↓+2 NaCl +2 silver nitrate == 2AgCl↓+ Ba(NO3) 2

5, salt+alkali → salt+alkali

Copper sulfate +2 NaOH solution = = Cu(OH)2↓+ sodium sulfate ferric chloride+3 NaOH = = Fe (OH) 3 ↓+3 NaCl < br/Ca (OH) 2+Na2CO3 = = calcium carbonate ↓+2 NaOH solution NaOH+ ammonium chloride = = NaCl+NH3 =+H2O.

Other reactions:

1 lime

The phenomenon of CO2+Ca(OH)2 = = CaCO _ 3 ↓+ H2O: carbon dioxide in lime water is clarified on cloudy days.

(It can be used to check and clarify CO2 in limewater, and it can also be used to check CO2 in lime. )

Calcium hydroxide reacts with sulfur dioxide: Ca (OH) 2+of SO2 = = caso3+H2O.

3. The reaction of calcium hydroxide, hydroxide and sulfur trioxide: Ca(OH)2+= = calcium sulfate +H2O of SO3.

4. In the reaction of sodium hydroxide and carbon dioxide (removing carbon dioxide): 2 NaOH+CO2 = = sodium carbonate +H2O.

5. Reaction between sodium hydroxide and sulfur dioxide (for removing sulfur dioxide): 2NaOH = = = sodium sulfite +H2O.

6. Reaction of sodium hydroxide with sulfur trioxide (removing sulfur trioxide): 2NaOH = = = sodium sulfate +H2O.

Note: 1-6: acid oxide+alkaline salt+water.

7 Methane burns in air: CH4+2O2 ignites CO2+2H2O.

Phenomenon: A bright blue flame is emitted on cloudy days to clarify the water droplets in the limewater beaker.

8. Alcohol burns air: C2H5OH+3O2 ignites 2CO2+3H2O.

Phenomenon: blue flame is emitted, and lime water on cloudy days is clarified in the water droplets in the beaker.

9. Reduction of copper oxide by carbon monoxide: CO+CuO+CO2 heats copper.

Phenomenon: black powder turns red, and lime water is clarified on cloudy days.

10, reduction of iron oxide by carbon monoxide: 3CO+Fe2O3, 2FE+3CO2 at high temperature.

Phenomenon: pink turns black, and lime water is clarified on cloudy days. (Reaction principle of ironmaking)

1 1 FeO+CO high temperature iron +CO2 reduction by iron oxide and carbon monoxide.

12, reduction of iron oxide by carbon monoxide: Fe3O4 +4 CO, high temperature 3fe+4co2br/>; 13 photosynthesis: 6CO2+6H2O light C6H 12O6 +6 O2.

14, glucose oxidation: c6h12o6+6o2 = = 6co2+6o2.

Scientific name, generic name and chemical formula of materials

(1) diamond, graphite: cυ mercury, mercury: mercury (3) quicklime, calcium oxide: CaO(4) dry ice (solid carbon dioxide): CO 2(5) hydrochloric acid, hydrochloric acid: hydrochloric acid (6) sulfite: H2SO4 3 (7) bisulfate: hydrogen sulfide (8) Caustic soda: Alkali in NaOH( 10): sodium carbonate crystal, soda ash, crystalline sodium carbonate 10H2O( 1 1) sodium bicarbonate, acidic sodium carbonate: sodium bicarbonate (also called baking soda) (12) alum. Malachite: Cu2(OH)2 CO 3 (a substance that can decompose oxide) (14) methanol: methanol is toxic, blinding and dead (15) alcohol, ethanol: ethanol (16), acetic acid, acetic acid (/kloc-0).

Second, common substances

1, a white solid color: magnesium oxide, phosphorus, calcium, sodium hydroxide, Ca(OH)2, potassium chlorate, potassium chloride, sodium carbonate, sodium chloride, anhydrous copper sulfate, iron, magnesium and silver (mercury-silver white liquid).

Black solid: graphite, charcoal powder and iron powder ▲ Potassium permanganate is purple and black.

3. Red solid: copper, iron oxide, mercuric oxide, copper oxide, manganese dioxide, ferroferric oxide red phosphorus ▲ sulfur: light yellow ▲ green to Cu2(OH)2CO3.

4. Color solution: one of the solutions, which contains Cu2+ blue solution and Fe2+ light green solution; Fe3+ solution is brownish yellow, while other solutions are generally colorless. (Potassium permanganate solution is purple)

5 Star, precipitate (i.e. salt and alkali insoluble in water): ① Salt: white calcium carbonate, barium carbonate (soluble in acid), silver chloride, barium sulfate (insoluble in dilute HNO) and other ② Alkali: blue: reddish brown: Cu(OH)2: iron (OH)3 White: the rest alkali.

6. (1) Gases with pungent odor: NH3, SO2 and hydrochloric acid (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. Special gas, liquid alcohol.

7. Toxic gas: CO liquid: CH3OH solid: sodium nitrite and copper sulfate (can be used as bactericide, and blue mixed hydrated lime is called viscous substance-Bordeaux liquid).

Solubility of three substances

1, other salts

Contains potassium, sodium, nitrate, ammonium and substances.

Only the AgCl of the compound containing Cl- is insoluble in water, soluble in water and soluble in water;

This compound contains SO42, only barium sulfate is insoluble in water, and others are soluble in water.

This substance contains CO32, the only potassium carbonate, sodium carbonate, (NH4)2CO3, which is soluble in water and the other is insoluble in water.

Alkali solubility: water-soluble alkali: barium hydroxide, potassium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydroxide and ammonia water, and other water-insoluble alkali. Fe(OH)3 of insoluble alkali is red-brown precipitate, Cu(OH)2 is white, and other water-soluble alkali is blue precipitate. (Including iron (OH)2) Note: AgCl and barium sulfate precipitates are insoluble in dilute nitric acid.

Other precipitates are soluble in acid. Such as calcium carbonate of magnesium hydroxide and barium carbonate AG2 CO3.

3. Most acids and acidic oxides are soluble in water. (Acidic oxide+water → acid) The most basic oxide is insoluble in water, but soluble in barium oxide, barium hydroxide, calcium oxide and sodium oxide (basic oxide+water → alkali).

Four chemical most

The most abundant metal element in the earth's crust is aluminum. As shown in Figure 2, the nonmetallic element in the earth's crust is oxygen.

The air component in this substance is nitrogen. As shown in Figure 4, the hardest natural material is diamond.

5. The simplest organic matter is methane. As shown in Figure 6, the most active metal in the active sequence list is potassium.

7. The oxide with the smallest relative molecular mass is water. The simplest organic compound CH4

8 method, under the same conditions, the gas with the lowest density is hydrogen. As shown in Figure 9, the strongest conductive metal is silver.

10, the relative atomic mass of the smallest hydrogen atom. As shown in figure 1 1, the melting point of the smallest metal is mercury.

12, the most abundant element in human body is oxygen. 13, the largest element of the compound is carbon.

14 The most widely used metal in daily life is iron. 15, the earliest natural gas used in China, and the largest coal base in China: Shanxi Province; China, the earliest user of wet copper (in the Western Han Dynasty [An Wan Yuan Shu in Huainan was once used as copper], was applied in the Song Dynasty), and Thomson, the earliest British, discovered electrons, and the earliest air was transferred from N2 and O2 to lavoisier, France.

Junior high school chemistry

A substance consisting of molecules, atoms and ions.

Reducing agents for reducing copper oxide: hydrogen, carbon monoxide and carbon.

3. Hydrogen as fuel has three advantages: rich resources, high heat, water as combustion product and no pollution to the environment. As shown in Figure 4, there are usually three types of particles that make up atoms: protons, neutrons and electrons. Five stars, there are only three kinds of ferrous metals: iron, manganese and chromium. The substances that make up elements can be divided into three categories, namely, metallic elements (1), nonmetallic elements (2) and (3) and rare gas elements.

7. There are three kinds of iron oxides, the chemical formula is (1), and the FeO in (2) is iron oxide (3) ferroferric oxide.

8,3 (1), (2) stability, (3) their mixture.

9. The chemical equation has three meanings: (1) indicates what substance participates in the reaction and what substance is the result; (2) the product of the Q ratio of each substance of reactants, particle atoms or molecules; There are two principles for the mass ratio between reactants and the generated chemical equation expressed by dosage (3): on the basis of objective facts, follow the law of conservation of mass. Pig iron is generally divided into three types: white cast iron, gray cast iron and ductile iron.

1 1 and carbon 10 steel are divided into three types: high carbon steel, medium carbon steel and low carbon steel.

12. There are three common ways to make iron ore: (1) hematite (with Fe2O3 as the main component), (2) ignited magnetite (Fe3O4), siderite (FeCO3)(3) 13, and (3) converter, electric furnace and open-hearth steelmaking equipment.

As shown in figure 15, there are two ways to change saturated solution into unsaturated solution: (1) heating, and (2) there are three ways to change unsaturated solution into solvent saturated solution: cooling, adding solute, heating, and evaporating solvent (note: saturated solution of substances with reduced dissolution temperature, such as calcium hydroxide solution, becomes unsaturated solution: cooling, adding solvent, unsaturated solution.

16, there are generally three methods to collect gas: drainage, ventilation and pumping up and down.

17, there are three main reasons for water pollution: (1) industrial production waste, waste gas and waste water; (2) Any sewage discharge (3) Rainwater generated by pesticides and fertilizers used in agricultural production flows into rivers.

18, there are three kinds of fire extinguishers commonly used, namely foam extinguisher, dry powder extinguisher and liquid carbon dioxide extinguisher 19. Solid substances whose solubility changes 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 less affected by temperature, and (3) the solubility of a few substances changes with temperature. 20 CO2 fire extinguishing Ⅲ does not burn or support combustion, and it is 2 1 heavier than air. Elemental substances can be divided into three categories: metals, nonmetals and inert gases, and the three most important fossil fuels in the world: coal, oil and natural gas. Remember three kinds of black oxides: copper oxide, manganese dioxide and iron oxide. 24. Simple substances such as hydrogen and carbon have three similar chemical properties: stability at room temperature, flammability and reducibility. 25, light blue three textbooks: (1) liquid oxygen is light blue (2) sulfur with light blue flame burns in the air, (3) hydrogen light blue flame burns in the air.

26. The three blue colors of copper are related: (1) sulfate crystallization of copper, (2) hydroxide precipitation of copper, and (3) copper sulfate solution. During the filtration operation: (1) The bottom of the funnel is close to the inner wall of the beaker; On the edge of the glass (3) at the end of the glass rod (2) of the filter paper layer, a beaker filled with the liquid to be filtered is kept drained.

28. Three kinds of gas pollutants SO2, CO and NO2.

29. It is divided into three parts: external flame, internal flame and flame core, among which the external flame temperature of alcohol lamp flame is the highest.

30. The "three noes" principle of obtaining drugs: (1) Don't touch drugs (2) Put your nose close to the mouth of the container and smell the odorous gas; (3) Do not taste medicine. 3 1, three major chemical processes in ancient times: papermaking, gunpowder and porcelain firing, and 32 industrial wastes, wastewater, wastes and waste gas.

34. Instruments that can be directly heated: test tubes, crucibles and evaporating dishes (except burning spoons).

It shows that the mass of atoms is conserved, the type will not change, and the quantity and mass will not increase or decrease.

36. Mixing with air may explode and ignite three gases: H2, carbon monoxide and methane (in fact, any combustible gas and dust). Three products of carbonized coal (chemical change): coke, coal tar and coke oven gas.

38, concentrated sulfuric acid 3 characteristics: water absorption, dehydration, strong oxidation

39. It is forbidden to use alcohol lamps: EEP will burn and alcohol will be ejected in the mouth.

40. Three steps of solution preparation: calculation, weighing (weight) and dissolving in

4 1, the first three biological cell content elements: o, c, h.

In the third category: nuclear charge number, atomic number = proton = extranuclear electron = atomic number.

Three particles make up the molecular atoms and ions of matter.

Six, chemicals "must" and "not necessarily"

There must be physical changes in chemical changes, and chemical changes are not necessarily physical changes.

2. At room temperature, all metals are not necessarily solid (for example, Hg is liquid), and all nonmetals are not necessarily gas or solid (for example, Br2 is liquid). Note: The quality of metal and nonmetal devices is single, but the material elements are not confused.

3. The group must carry ions, but the free radical is not necessarily an acid radical (such as NH4+, OH-);

The divalent anion is not necessarily a free radical (for example, the so-called Cl- hydrogen perchlorate)

4. Slow oxidation does not necessarily lead to spontaneous combustion. Must combustion be a chemical change? Change. Explosion is not necessarily a chemical change (for example, pressure cooker explosion is a physical change. ) 5 stars, the nucleus does not necessarily have neutrons (such as H atom neutrons) 6, atoms are not necessarily smaller than molecules (it cannot be said that "molecules are big and atoms are small".

The fundamental difference between molecules and atoms In chemical reactions, molecules and atoms are inseparable.

7. Components with the same composition can be divided into a single substance, which may be a mixture of several single masses.

The outermost electrons of 8,8 particles are not necessarily atoms of rare gas elements, but also cations or anions. As shown in fig. 9, the number of atoms of the outermost electron in the stable structure is not necessarily 8. (The first layer is the outermost two electrons) 10, and the number of particles with the same nuclear charge is not necessarily the same element.

(Because particles including atoms, molecules, ions and elements do not include polyatomic molecules or atomic groups), only single nuclear particles (nuclei) with the same mass must belong to the same element.

The concentrated solution of 1 1, (1) is not necessarily a saturated solution, and the dilute solution is not necessarily an unsaturated solution. (For different solutes) (2) The substances in saturated solution are not necessarily more concentrated than those in unsaturated solution. (Because the temperature has not been determined, the temperature is constant), and (3) the crystallization of the solution after that must be in a saturated solution of a substance. It is not necessary to cool the saturated solution to precipitate crystals. (4) At a certain temperature, the solubility of any substance must be greater than the mass fraction of solute in saturated solution, that is, S must be greater than C.. 13, and the simple substance and participating compounds, or the resulting reaction, may not be a displacement reaction. But the valence of elements is definitely changing. 14, decomposition reaction and recombination reaction do not necessarily change the valence of elements; Change the valence of some elements in the substitution reaction; The metathesis reaction of elements certainly has no valence change. (Note: Redox reaction changes the valence of some elements) 15, and no simple decomposition reaction will occur.

16 does not necessarily mean that the same valence elements are in the same compound. For example, ammonium nitrate and (the price of N -3 in front and the price of N-3 in the back) 17, the composition of the salt is not necessarily a metal element. For example, NH4+ is a cation, which has the properties of a metal ion, but it is not a metal ion. 18, the cation is not necessarily a metal ion. Such as H+, NH4+.

19, composed of compounds (oxide, acid, alkali, salt), oxide of oxygen element and an alkali must be included; Acids and salts of oxygen that must be included (possible); Acids and bases that must contain hydrogen; Elements are not necessarily hydrogen-containing salts and oxides; Salt and alkali metal elements (such as ammonium nitrate, NH3·H2O) are not necessarily in the composition; Lactic acid components can contain metallic elements (for example, HMnO4 is called high manganese), but all material components must contain nonmetallic elements. As shown in fig. 20, the salt solution is not necessarily neutral. Na2CO3 solution is alkaline. 2 1, the acidic salt solution is not necessarily significant (that is, the PH value must be less than 7), for example, the NaHCO 3 solution is alkaline. However, sodium bisulfate (Na ++ h++ SO42-= of sodium bisulfate) is in an obviously acidic solution, so the hydrogen ions that can be ionized are not necessarily acidic. 22. The acidic solution must be in the acidic solution. In an acidic solution, it is not necessarily an acidic solution. For example, in H 2 SO 4, the sodium bisulfate solution is acidic and the metal salt is sodium bisulfate. (acid solution of acid solution means that the solution contains H +)23. An alkaline solution is necessary, but not necessarily an alkaline solution. For example, sodium hydroxide, sodium carbonate and sodium bicarbonate solutions are all alkaline, and sodium carbonate and sodium bicarbonate salts. Alkali of alkaline solution, alkaline solution means that the solution containing OH-)24 is an aqueous solution, and the alkaline oxide must be a metal oxide, and the metal oxide is not necessarily an alkaline oxide.

(such as Mn2O7 metal oxide, but it is the high manganese of the acid corresponding to the acid oxide, i.e. HMNO4); Remember: the basic oxides are only potassium oxide, sodium oxide, BaO and CaO, which are produced in water-soluble reactions and are based on water.

25. The above acidic oxides are not necessarily nonmetallic oxides, such as Mn2O7 nonmetallic oxides, and are not necessarily acidic oxides (such as H 2 O, CO, NO). ★ Common acidic oxides: CO 2, SO 2, SO 3, P 2 O 5, silica, etc. Most acidic oxides are soluble in water and react with corresponding acids. Remember that silicon dioxide (SiO2) is insoluble in water.

26. The reaction between salt and water is not necessarily a neutralization reaction.

27. All chemical reactions do not necessarily belong to the basic type. In the absence, the basic reactions are as follows: ①CO reacts with metal oxides; (2) acidic oxides that react with alkali, and (3) organic combustion.

28. Any single high-quality iron participates in the displacement reaction (the salt of iron and acid, in the reaction), and after the reaction, there must be significant divalent iron (that is, the generated ferrous salt). 29, in which metals and acids undergo substitution reaction, and the quality of the solution must be improved after the reaction.

The reaction of any metal salt solution determines the reaction before and after the quality change of the solution, and depends on the relative atomic mass of the metals involved in the reaction. "Big and small weight gain, big and small weight loss.

In any country where metals react with acids, the same mass and price react, and the larger relative atomic mass produces the mass of hydrogen. 3 1, in which metals that can react with water at room temperature (such as K, Ca, Na) will certainly not react with salt solution, but react with acid most strongly.

Such as Na CuSO4 solution, the reaction occurs: 2na+2h2o = 2n NaOH+H2 ↑; CuSO4 of 2NaOH = Cu (OH) 2 ↓+Na2SO4.

On 3 1, Hong Kong's exclusive air waybill (up or down), please confirm that the airway enters the bottom of the container.

32. Before preparing the gas generator and loading drugs, be sure to check the air tightness.

Before burning or heating combustible gas, its purity must be tested.

In the formula of writing 33, the positive element is not necessarily written on the left. Such as NH3, CH4

The solute mass fraction of 34.5g substance to 95g water is not necessarily equal to 5%.

Can be equal to 5%, such as sodium chloride, potassium nitrate, etc. , or more than 5%, such as BaO and SO3； of K 2 O and Na2O; It can also be less than 5%, such as crystalline hydrate and Ca(OH)2, CaO, etc.

◆ Under the same conditions, when CaO or Ca(OH)2 is dissolved in water, the mass fraction of solute in the obtained solution is the lowest.