I am a senior, soon to be high school, also reported chemistry, there are many answers on the Internet, I'll give you an intercept point useful, within the scope of the syllabus
Carbon oxygen group in the syllabus are not a separate classification to speak, because of its involvement in the face of a relatively large number of: AL and Fe are separate chapters
Carbon elemental introduction
Carbon is a non-metallic element, located in the elemental group IVA in the second period of the periodic table.
Carbon is a very common element, and it is widely found in the atmosphere and the Earth's crust in many forms. Carbon monomers were recognized and utilized early on, and a series of compounds of carbon - organic matter - are fundamental to life. Carbon is one of the components of pig iron, mature iron and steel. Carbon is capable of chemically combining itself to form a large number of compounds and is an important molecule biologically and commercially. Most molecules in living organisms contain the element carbon[1].
Carbon compounds are generally obtained from fossil fuels, which are then separated and further synthesized to produce various products needed for productive life, such as ethylene and plastics.
Carbon exists in a variety of forms, including crystalline monomorphic carbon such as diamond and graphite; amorphous carbon such as coal; complex organic compounds such as plants and animals; and carbonates such as marble. The physical and chemical properties of monomeric carbon depend on its crystal structure. High hardness of diamond and soft and slippery graphite crystal structure is different, each with its own appearance, density, melting point and so on.
At room temperature, the chemical properties of simple carbon is relatively stable, insoluble in water, dilute acid, dilute alkali and organic solvents; different high temperatures and oxygen reaction, generating carbon dioxide or carbon monoxide; only fluorine in the halogens and simple carbon direct reaction; in the heating, simple carbon is easier to be oxidized by the acid; at high temperatures, carbon can also be with the reaction of many metals to generate metal carbides. Carbon is reductive and can smelt metals at high temperatures.
Chemical symbol: C
Proton number: 6
Atomic number: 6
Cycle: 2
Group: IVA
Distribution of electron layers: 2-4
Electron configuration : 1s22s22p2
Oxide valence (oxides): 4, 3. C+2, C+4 (and other oxidation states)
Chemical bonding energy: (kJ /mol) C-H 411 C-C 348 C=C 614 C≡C 839 C=N 615 C≡N 891 C=O 745 C≡O 1074
Bonding: Carbon atoms are generally tetravalent, which requires four single electrons, but its base state has only two single electrons. So bonding always involves hybridization. The most common hybridization is sp3 hybridization, 4 valence electrons are fully utilized, evenly distributed in 4 orbitals, belonging to isotropic hybridization. This structure is completely symmetrical, and after bonding it is a stable σ-bond, and it is very stable without the repulsion of lone electron pairs. All carbon atoms in diamond are bonded in this hybridized way. The carbon atoms of alkanes also belong to this category.
Note the electronic formula of CO2 and its crystal type, it will be written
Note that diamond and graphite are the same element, just different due to their internal structure
Much of organic has to do with carbon!
Oxygen
Elemental Property Data
Element symbol:O
Relative atomic mass:16
Oxidation state:
Main -2
Other -1, 0, +1, +2
Elemental description:
Normally a colorless, odorless and tasteless Gas. Density 1.429 g/l, 1.419 g/cm3 (liquid), 1.426 g/cm3 (solid). Melting point -218.4 ℃, boiling point -182.962 ℃, in -182.962 ℃ liquefied into a light blue liquid, in -218.4 ℃ solidified into a snow-like light blue. Solid in the valence is generally 0 and -2. Ionization energy is 13.618 eV. All chemical elements except noble gases can form compounds with oxygen. Most elements can form oxides when heated in an oxygen-containing atmosphere. There are many elements that form more than one oxide. Oxygen molecules can form hydrated crystals O2.H2O and O2.H2O2 at low temperatures, the latter being less stable. The solubility of oxygen in air is: 4.89 ml/100 ml of water (0°C) and is the basis for life forms in water. Oxygen is first in abundance in the earth's crust. Dry air contains 20.946% oxygen by volume; water is composed of 88.81% oxygen by weight. In addition to O16, there are O17 and O18 isotopes.
Source of the element:
Oxygen can be produced in the laboratory by heating mercuric oxide in a glass container or by decomposing nitrates and by using concentrated sulfuric acid with manganese dioxide. Oxygen is usually produced in the laboratory by heating potassium permanganate, can also be used to heat potassium chlorate and manganese dioxide mixture of oxygen; catalyzed decomposition of hydrogen peroxide [1] (hydrogen peroxide) with a catalyst can also be convenient to produce oxygen. Large-scale production of oxygen and the purity requirements are not high when the use of air liquefaction and fractional distillation to be carried out, a small amount of oxygen or higher purity of oxygen produced by electrolysis of water.
Elemental Uses:
Oxygen is used in large quantities in metallurgical processes such as smelting, refining, welding, cutting, and surface treatments; liquid oxygen is a refrigerant and an oxidizer for high-energy fuels. It and sawdust, coal dust mixture called liquid oxygen explosive, is a better explosive material, oxygen mixed with water vapor, can be used to replace the air blown into the coal gasifier, can get a higher calorific value of the gas. Liquid oxygen can also be used as rocket propellant; oxygen is the basic component of many biological processes, so oxygen has also become the burden of any mission in space is required to load a large number of necessities. Oxygen therapy is used medically to treat hypoxia such as pneumonia and gas poisoning. Mining, production and creation of stone and glass products require large amounts of oxygen.
Elemental aids:
Oxygen is a major component of air. Many oxygen compounds, such as potassium nitrate and mercuric oxide, give off oxygen when heated. Oxygen is the most abundant of all elements in the earth's crust. All these indicate that oxygen may have been obtained by people very early. However, because oxygen is in the usual state to the gas condition exists, and can be accessed, visible solid, liquid different, so that people simply with intuitive observation, is not able to recognize it.
From the 16th century, in Western Europe, many researchers on the heating of oxygen-containing compounds to obtain the gas, the air in the combustion of substances and animal respiration in the role of the initial scientific chemical experiments, so that the discovery of oxygen. It was only after the phenomenon of combustion was properly recognized and oxygen was discovered that the combustion theory was completely disproved.
Properties This product is a colorless gas; odorless, tasteless; strong combustion power.
The product 1 volume at atmospheric pressure at 20 ℃, can be dissolved in ethanol 7 volume or water 32 volume.
Identification This product can make the blazing red wood suddenly flare up and burn.
The chapter on oxygen in high school involves redox reactions, which can be done through the idea of conservation during the questions
This teacher will talk about it!
Aluminum
A metal element, symbol AI, silver-white, shiny, tough and light, ductile, do daily utensils of aluminum usually called steel fine or steel species.
Element Name: Aluminum
Element Symbol: Al
Type of Element: Metal
Proton Number in Nucleus: 13
Electron Number in Nucleus: 13
Nuclear Nucleus Number: 13
Oxidation State: Main Al+3
Other Al0, Al+2
Belonging Period: 3
Other Al0, Al+2
Period:3
Group:IIIA
Molar mass:27
Hydroxide:AlH3
Oxide:Al2O3
Maximum-valent oxide formula:Al2O3
Elemental origin:The most abundant metal in the earth's crust, more than 7%
Elemental uses Aluminum: It can be used as structural material for airplanes, vehicles, ships, boats, and rockets. Pure aluminum can be made of ultra-high voltage cables. Do daily utensils of aluminum is usually called "steel fine", "steel species"
Industrial production: electrolysis of a mixture of molten alumina and cryolite
Other compounds: AlCl3-aluminum chloride NaAlO2-sodium meta-aluminate Al(OH)
Other compounds: AlCl3-aluminum chloride NaAlO2-sodium meta-aluminate Al (OH)3-aluminum hydroxide
Extended description: bluish, silvery-white, trivalent metallic element, malleable, ductile and capable of making a [loud] sound, known for its lightness, good electrical and thermal conductivity, high reflectivity and resistance to oxidation.
Source
Aluminum exists in various rocks or ores as a chemosynthetic form, such as feldspar, mica, kaolin city, bauxite, alum when, and so on. There are oxides of aluminum produced by fusion electrolysis with cryolite (Na3AlF6)****.
Extraction of aluminum from bauxite reaction process
① Dissolution: dissolve bauxite in NaOHaq.
Al2O3+2NaOH=2NaAlO2+H2O
② Filtration: remove the residue of iron oxides, sodium silicate and so on
③ Acidification: to the filtrate pass an excess of CO2.
NaAlO2+CO2+2H2O= Al(OH)3↓+NaHCO3
④ Filtering, scorching Al(OH)3
2Al(OH)3= Al2O3+3H2O (high temperature)
Note: Electrolysis for the purpose of making the alumina melting temperature is reduced, in the Al2O3 added cryolite (Na3AlF6)
⑤ Electrolysis: 2Al2O3 (molten) = 4Al + 3O2 ↑ (energized)
Note: not electrolysis of molten AlCl3 refining Al Reason: AlCl3 is a *** valence of compounds, the molten state of its non-conductive.
Uses
Aluminum can be used to displace metals from other oxides (Aluminum Heat Method). Its alloys are light and tough, and are used as structural materials in the manufacture of airplanes, rockets, and automobiles. Pure aluminum is used in large quantities in cables. It is widely used to make everyday utensils.
Aluminum and its alloys
Pure aluminum is very soft, not very strong, has good ductility, can be drawn into fine wire and rolled into foil, a large number of used in the manufacture of wires, cables, the radio industry, and packaging industry. Its conductive capacity of about two-thirds of copper, but because of its density is only one-third of copper, therefore, will be equal to the quality and length of aluminum and copper wire compared to the conductive capacity of aluminum is about two times as much as copper, and the price is lower than the price of copper, so the wild high-voltage line made of aluminum, saving a lot of cost, easing the tension of the copper material.
Aluminum's thermal conductivity is three times greater than iron, aluminum is commonly used in industry to manufacture a variety of heat exchangers, heat dissipation materials, etc., home use of many cooking utensils are also made of aluminum. Compared with iron, it is also not easy to rust and corrosion, extending the service life. Aluminum powder has a silvery-white luster, often mixed with other substances used as paint, brushed on the surface of iron products, to protect iron products from corrosion, and beautiful. As aluminum in the oxygen combustion can emit dazzling white light and release a lot of heat, and often used to make some explosive mixtures, such as ammonium-aluminum explosives.
Metallurgical industry, commonly used aluminum thermite to melt refractory metals. Such as aluminum powder and iron oxide powder mix, after the trigger that is a violent reaction, the traffic is often used to weld the rail; steel industry, aluminum is often used as a deoxidizer; clean aluminum plate has a good light reflection performance, can be used to manufacture high-quality reflector, poly-light bowl. Aluminum also has good sound-absorbing properties, according to this feature, - some broadcasting rooms, modern large buildings within the ceiling, etc. Some of the use of aluminum. Pure aluminum is softer, in 1906, the German metallurgist Vilm in aluminum to add a small amount of magnesium, copper, made a tough aluminum alloy, later, this patent for the German Dura company to buy, so the aluminum and have "Dura Aluminum," the name, in the process of development in the next few decades, according to the different needs of the development of many aluminum alloys in many areas play a very important role in the development of the aluminum alloy, the aluminum alloy is a very important role in the development of the aluminum alloy. Many fields play a very important role.
Adding a small amount of aluminum to certain metals can greatly improve their performance. Such as bronze aluminum (containing aluminum 4% to 15%), the alloy has a high strength corrosion resistance, hardness and mild steel close to, and has a metal luster is not easy to darken, commonly used in jewelry and construction industry, the manufacture of machine parts and tools, used for pickling equipment and other equipment with dilute sulfuric, hydrochloric and hydrofluoric acids in contact with the equipment; the production of welder brushes and clamp handles; heavy-duty gears and worm gears, metal molding molds, machine tool guide, no sparks, tooling, and the use of aluminum alloys. Aluminum is also used in the production of non-sparking tools, non-magnetic chains, pressure vessels, heat exchangers, compressor blades, ship propellers and anchors, and so on. Add magnesium in the aluminum, it is made of aluminum-magnesium alloy, its hardness than pure magnesium and aluminum are much larger, and retains its lightweight characteristics, commonly used in the manufacture of aircraft fuselage, rocket arrows; the manufacture of windows and doors, landscaping environment; the manufacture of ships.
Aluminizing, is a chemical heat treatment of steel, so that the surface of ordinary carbon steel or cast iron to form a high-temperature-resistant aluminum oxide film to protect the internal iron. Aluminum is a very important metal, however, many aluminum-containing chemicals are also very significant for humans.
Aluminum-containing compounds
Aluminum in the earth's crust, the content of high, after silicon and oxygen and ranked third, mainly in the aluminosilicate ores, but also bauxite and cryolite. Aluminum oxide is a white amorphous powder, it has a variety of variants, the most familiar is α-A12O3 and β-Al2O3. natural existence of corundum that belongs to the α-Al2O3, its hardness is second only to diamond, high melting point, acid and alkali resistance, commonly used in the production of a number of bearings, the manufacture of abrasive materials, refractory materials. Such as corundum crucible, can withstand 1800 ℃ high temperature. Corundum has various colors due to different impurities. For example, containing traces of Cr (III) is red, known as ruby; containing Fe (II), Fe (III) or Ti (IV) known as sapphire.
β a A12O3 is a porous material, each gram of internal surface area can be as high as hundreds of square meters, has a high activity, also known as activated alumina, can adsorb water vapor and many other gases, liquid molecules, commonly used as adsorbents, catalyst carriers and desiccants, etc., industrial smelting of aluminum is also used as a raw material.
Aluminum hydroxide can be used to prepare aluminum salts, adsorbents, mordants and ion exchangers, can also be used as porcelain enamel, refractory materials, fireproof cloth and other raw materials, its gel liquid and a thousand gels in medicine used as an acid medicine, and have neutralized gastric acid and the treatment of ulcers, used in the treatment of gastric and duodenal ulcer disease and gastric hyperacidity.
Sodium meta-aluminate is commonly used in printing and dyeing fabrics, the production of lake blue dyes, the manufacture of woolen glass corrosion, soap, hardened building stone. In addition, it is also a good water softener, filler for paper making, water purifier, rayon de-reflective agent and so on.
Anhydrous aluminum chloride is a commonly used catalyst in the petroleum industry and organic synthesis; for example: the alkylation reaction of aromatic hydrocarbons, also known as Fourierdale-Krafts alkylation reaction, catalyzed by anhydrous aluminum trichloride, the aromatic hydrocarbons with halogenated hydrocarbons (or olefins and alcohols) electrophilic substitution reaction to generate the aromatic hydrocarbons alkyl substituents. Aluminum chloride hexahydrate is used in the preparation of deodorants, safety disinfectants and petroleum refining.
Aluminum bromide is commonly used as a catalyst for organic synthesis and isomerization.
Aluminum phosphide meets moisture or acid to release highly toxic phosphine gas, which can poison pests, and is used in agriculture as a fumigant to kill insects in barns.
Aluminum sulfate is commonly used as filler for paper, mordant, water purifier and fire extinguisher, grease clarifier, oil deodorant and decolorant, and is used to make precipitated pigment, fireproof cloth and drugs.
Cryolite is sodium hexafluoroaluminate, commonly used in agriculture as an insecticide; silicate industry for the manufacture of glass and enamel emulsifier.
Alum is an important water purifier, dyeing medium, and used as an astringent in medicine, which is produced by heating and extracting alum. Aluminum nitrate can be used for tanning and white thermoelectric filament, can also be used as a mordant; aluminum silicate is commonly used in the production of glass, ceramics, paint pigments and paints, rubber and plastic fillers, aluminum silicate gel with hygroscopicity, often used as a catalyst for catalytic cracking of petroleum or other organic synthesis carrier.
In the carboxylates of aluminum; aluminum dicarboxylate, aluminum triformate is commonly used as mordant, waterproofing agent and fungicide, etc.; aluminum diacetate in addition to mordant, but also be used as a sword retractor and disinfectant, but also used for corpses in the antiseptic solution; aluminum triacetate is used in the manufacture of waterproof and fire-resistant fabrics, color precipitates; medicines (gargles, astringents, antiseptic, etc.), and used as mordants, etc.; octadecanoic acid aluminum (aluminum stearate) is often used for Anti-sedimentation agent of paint, waterproofing agent of fabric, thickening agent of lubricating oil, antirust oil agent of tools, heat-resistant stabilizer of PVC plastics, etc.; Aluminum oleate is used as a waterproofing agent of fabrics and thickening agent of lubricating oil, but also used as a drying agent of paint and lubricant of plastic products.
Aluminum thioglycollate, also known as gastric ulcer, the scientific name of sucrose sulfate alkaline aluminum salt, which can be complexed with pepsin, direct inhibition of proteolytic activity, the role of the more durable, and can form a protective film, the gastric mucosa has a strong protective effect and acid production, to help regeneration of the mucosa, to promote the healing of ulcers, low toxicity, is the mouth of the kind of good gastrointestinal ulcers therapeutic agents.
In recent years, people have developed some new aluminum compounds, such as alkyl aluminum, with the development of science, people will be better use of aluminum and compounds for human beings.
Aluminum-related chemical equations:
2AL+6HCL=2ALCL3+3H2↑
2AL+3H2SO4=AL2(SO4)3+3H2↑
2Al+2NaOH+2H2O=2NaAIO2+3H2↑
2Al(OH)3=(heated) Al2O3+H2O
Al2(SO4)3 + 6NH3.H2O = 2Al(OH)3↓ + 3(NH4)2SO4
Al2O3 + 6HCl = 2AlCl3 + 3H2O
Al2O3 + 2NaOH + 3H2O = 2Na[Al(OH)4]
AlCl3+3NaOH=Al(OH)3↓+3NaCl
Al(OH)3+NaOH=Na[Al(OH)4]
AlCl3+3NaOH=Al(OH)3↓+3NaCl
Al2(SO4)3 ＋ 6 NaHCO3=2 Al(OH)3↓+ 3 Na2SO4 ＋ 6 CO2↑
NaAlO2 ＋ HCl (small amount) + H2O = Al(OH)3↓ + NaCl
Al(OH)3 ＋ 3 HCl = AlCl3 ＋ 3 H2O
NaAlO2 ＋ 4 HCl (excess) = AlCl3 ＋ NaCl ＋ 2 H2O
2 NaAlO2 ＋ CO2 ＋ 3 H2O = 2 Al(OH)3↓ + Na2CO3 Strong acid to make weak acid
AL words note his 2 nature, that is, reflected with both acidic and basic, and also note his ionization equation, the method of preparation and the salt of the AlO2-root
Iron Fe
The chemical properties of iron
[One of the chemical properties of iron].
Iron Fe, atomic number 26, relative atomic mass 55.847. iron has a variety of isotopes, such as α-iron, β-iron, γ-iron, б-iron and so on. Iron is a more active metal, in the order of metal activity table in front of hydrogen. At room temperature, iron in dry air is not easy to react with oxygen, sulfur, chlorine and other non-metallic monomers, but at high temperatures, it reacts violently. Iron burns in oxygen, generating Fe3O4, hot iron and water vapor reaction also generates Fe3O4. iron is easily soluble in dilute inorganic acid and concentrated hydrochloric acid, generating divalent iron salts, and release of hydrogen. At room temperature when met with concentrated sulfuric acid or concentrated nitric acid, the surface generates a layer of oxide protective film, so that iron "passivation", so we can use iron products containing concentrated sulfuric acid or concentrated nitric acid. Iron is a variable element, common valence +2 and +3. Iron and sulfur, copper sulfate solution, hydrochloric acid, dilute sulfuric acid, etc. when the reaction of the loss of two electrons, to become +2 valence. When it reacts with Cl2, Br2, nitric acid and hot concentrated sulfuric acid, it is oxidized to Fe3+. Iron reacts with oxygen or water vapor to produce Fe3O4, which can be seen as FeO-Fe2O3, of which 1/3 of Fe is +2 valence, and the other 2/3 is +3 valence. The +3 valence compounds of iron are more stable.
[Iron's chemical properties of the second]
Iron's electronic configuration is (Ar)3d64s2, oxidation state 0, +2, +3, +4, +5, +6. Iron's chemical properties of active, strong reductant, at room temperature can be slowly replaced from the water out of the hydrogen in 500 ℃ and above the rate of the reaction increases:
3Fe + 4H2O=== Fe3O4+4H2↑
Iron in dry air is difficult to interact with oxygen, but in the humid air is very easy to corrode, if it contains acidic gas or halogen vapors, corrosion is more rapid. Iron can be reduced from a solution of gold, platinum, silver, mercury, bismuth, tin, nickel or copper ions, such as:
CuSO4+Fe===FeSO4+Cu
Iron is dissolved in non-oxidizing acids, such as hydrochloric and dilute sulfuric acid, the formation of divalent iron ions and the release of hydrogen; in cold dilute nitric acid, the formation of divalent iron ions and ammonium nitrate:
Fe + H2SO4== =FeSO4+H2SO4== =FeSO4+H2SO4+H2S. =FeSO4+H2↑
4Fe+10HNO3===4Fe(NO3)2+NH4NO3+3H2O
Iron dissolved in hot or concentrated nitric acid produces iron nitrate and releases oxides of nitrogen. In concentrated nitric acid or cold concentrated sulfuric acid, the surface of the iron is passivated by the formation of an oxide film. Iron reacts violently with chlorine when heated. Iron can also be directly hydrated with sulfur, phosphorus, silicon, and carbon. Iron does not chemically combine directly with nitrogen, but interacts with ammonia to form Fe2N, iron nitride.
The most important oxidation states of iron are +2 and +3. Divalent iron ions are light green in color and are readily oxidized to trivalent iron ions in alkaline solutions. The color of trivalent iron ions changes from yellow to brown via orange as the degree of hydrolysis increases. Pure trivalent iron ions are lavender in color. Both divalent and trivalent iron can easily form stable coordination compounds with inorganic or organic ligands, such as Phen for phenanthroline, the coordination number is usually 6. Zero-valent iron can also be formed with carbon monoxide to form a variety of iron carbonyls, such as Fe(CO)5, Fe2(CO)9, Fe3(CO)12. Iron carbonyls have a volatile vapor, and the vapors are highly toxic. Iron also has compounds with +4, +5, and +6 valence, but only +6 in aqueous solution.
Compounds There are two main categories: ferrous Fe (Ⅱ) and ortho-ferrous Fe (Ⅲ) compounds, ferrous compounds are ferrous oxide, ferrous chloride, ferrous sulfate, ferrous hydroxide, etc.; ortho-ferrous compounds are ferrous oxide, ferrous trichloride, ferrous sulfate, ferrous hydroxide, and so on.
Such as in potassium ferricyanide K4[Fe(CN)6]-3H2O (common name: yellow blood salt) and potassium ferricyanide K3[Fe(CN)6] (common name: red blood salt). Ferrocene, the compound of iron and cyclopentadiene, is a metal-organic compound with a sandwich structure.
Iron's chemical properties of the three states
Iron's electronic configuration is (Ar)3d64s2, the oxidation state has 0, +2, +3, +4, +5, +6. Iron's chemical properties are active, a strong reducing agent, at room temperature can be slowly displaced from the water to hydrogen, the rate of the reaction at 500 ℃ above the increase in the rate of reaction: 3Fe + 4H2O ===Fe3O4 + 4H2
Iron in dry air is difficult to interact with oxygen, but in humid air is easy to corrode, if containing acidic gas or halogen vapor, corrosion is faster. Iron can be reduced from a solution of gold, platinum, silver, mercury, bismuth, tin, nickel or copper ions, such as: CuSO4+Fe===FeSO4+Cu
Iron is dissolved in non-oxidizing acids such as hydrochloric acid and dilute sulfuric acid, the formation of divalent iron ions and the release of hydrogen; in the cold of dilute nitric acid, the formation of divalent iron ions and ammonium nitrate:
Fe + H2SO4===FeSO4 + H2↑ 4Fe+10HNO3===4Fe(NO3)2+NH4NO3+3H2O
Elemental Sources
Iron is one of the more abundant elements in the earth's crust, after oxygen, silicon and aluminum. Magnetite, hematite, limonite and rhodochrosite are important iron ores. The monomer metal is commonly made from coke, iron ore and carnallite. Pure iron is obtained by reducing pure iron oxide with hydrogen. Iron containing more than 1.7% carbon is called pig iron (or cast iron). Iron fusions containing less than 0.2% carbon are called mature iron or wrought iron. Molten iron containing between 1.7 and 0.2% carbon is called steel. Pig iron is hard, but brittle; steel is elastic; cooked iron is easy to machine, but softer than steel. Steelmaking from pig iron is to reduce the amount of carbon within the pig iron, as well as silicon, sulfur and phosphorus impurities removed.
Elemental Uses
Its greatest use is in steelmaking; it is also used in large quantities in the manufacture of cast iron and calcined iron. Iron and its compounds are also used as magnets, dyes (inks, bluetints, cochineal pigments), and abrasives (red iron powder). Reduced iron powder is used in large quantities in metallurgy.
Elemental Supporting Information
One of the major components of the Earth's crust. Iron is extremely widely distributed in nature, but mankind discovered and utilized iron later than gold and copper. This is first of all due to the natural monomorphic state of iron on earth is not found, and it is easy to oxidize rust, coupled with its melting point (1535 ° C) than copper (1083 ° C) is much higher, so that it is difficult to melt than copper.
For iron, note that he has +2 and +3 valences, and here it's time to mention the use of ferrous and ferrous ions in redox reactions. Also note Fe3O4, a mixture of FeO and Fe2O3
Note the 2 high school equations focusing on Fe
3Fe+8HNO3 (dilute)===3Fe(NO3)2+2NO+4H2O
Fe+4HNO3 (dilute)====Fe(NO3)3+No+2H2O
For the same amount of Fe, the latter equation has a larger amount of nitric acid and can oxidize Fe to +3-valent Fe ions, while the first one can only oxidize to +2-valent ferrous ions due to the small amount of nitric acid