Fe (Iron) is a metallic element, atomic number sequence 26, elemental iron Chemical Formula: Fe. Pure iron is white or silvery white with a metallic luster. Iron Deficiency
The melting point of 1538 ° C, the boiling point of 2750 ° C, soluble in strong acid and medium-strong acid, insoluble in water. Iron has 0 prices, +2 price, +3 price and +6 price, of which +2 price and +3 price are more common, and +6 price is rare.
Iron is widely distributed in life, accounting for 4.75% of the crust content, second only to oxygen, silicon, and aluminum, ranking fourth in the earth’s crust.
Pure iron is a flexible and ductile silver-white metal used in the core of generators and motors. Iron and its compounds are also used in magnets, drugs, inks, pigments, abrasives, etc. which is industrially stated. One of the “black metals” (the other two are chromium and manganese)
In fact, the pure pig iron is silvery-white, the iron element is called “ black metal “ because the iron surface is often covered with a layer of the main component black tetraoxide. Three iron protective film.
In addition, the human body also contains iron, and the +2 ferrous ion is an important component of hemoglobin for the transport of oxygen.
The main iron ores used are: Fe2O3 (hematite), Fe3O4 (magnetite), FeCO3 (siderite), FeS2 (pyrite).
Physical and chemical properties
Appearance and shape: Pure iron is a metal crystal with a silvery-white metallic luster, usually in the form of gray to grayish black high-purity iron-colored amorphous fine particles or powder.
Has good ductility, electrical conductivity, thermal conductivity.
Strong ferromagnetic belongs to the magnetic material.
The specific heat capacity is 460 J / (kg·°C).
The rate of sound propagation in iron: 5120 m/s.
Pure iron is soft, but if it is an alloy of iron with other metals or iron with impurities, the melting point is usually lowered and the hardness is increased.
Crystal structure: face-centered cubic and body-centered cubic.
The relative atomic mass of iron is 55.85, and the ground state atomic electronic arrangement is: 1s 22s 22p 63s 23p 6 3d4s. (Bold part is valence electron)
Iron is an indispensable metal in the industrial sector. Iron is alloyed with a small amount of carbon — steel, which is not easily demagnetized after magnetization. It is an excellent hard magnetic material and an important industrial material, and also serves as the main raw material for artificial magnetism. Iron has a variety of allotropes.
Iron is more reactive metal, the metal active sequence table in the front row of hydrogen, the chemical nature of the lively, is a good reducing agent. Iron can’t burn in the air, but it can burn violently in oxygen.
Iron is a variable element, zero is only reducing, +6 is only oxidizing, +2, +3 is both reducing and oxidizing. In the displacement reaction, generally +2 valence, but a few valences +3, such as ferrous bromide and excess chlorine reaction:
At normal temperature, iron does not easily react with non-metallic elements such as oxygen, sulfur, chlorine, etc. in dry air.
If there are impurities, it is easy to rust in humid air; it is produced in the presence of acid, alkali or salt solution in the humid air. Rust is faster.
At high temperatures, violent reactions, such as iron burning in oxygen, produce Fe 3O 4, and a red hot iron and water vapor react to form Fe 3O 4.
When heated, it can be combined with halogen, sulfur, silicon, carbon, phosphorus, and the like. In addition to the formation of the +2 and +3 valence oxides, the composite oxide Fe 3O 4 (the main component of the magnet) is formed.
Iron is easily dissolved in a dilute mineral acid to form a divalent iron salt and to release hydrogen.
When concentrated sulfuric acid or concentrated nitric acid is encountered at normal temperature, an oxide protective film is formed on the surface to “passivate” the iron, so that cold concentrated sulfuric acid or cold concentrated nitric acid can be used for the iron product.
Upon heating, the iron can be reacted with concentrated sulfuric acid or concentrated nitric acid to form a +3 valent iron salt while forming SO 2 or NO 2.
The burning of iron wire in oxygen (as shown on the right):
At high temperatures, iron burns in pure oxygen, reacts violently, and Mars is four-shot, producing Fe 3O4, and Fe 3O 4 can be regarded as FeO·Fe 2O 3. Reaction equation:
The reaction of iron with non-oxidizing dilute acid (displacement reaction)
In general, iron reacts with dilute sulfuric acid to form ferrous sulfate, and bubbles are generated. In reality, it is more complicated.
However, if the iron is concentrated, the concentrated sulfuric acid or concentrated nitric acid will passivate, and a dense oxide film (main component Fe 3O 4) will be formed. Therefore, the concentrated sulfuric acid and concentrated nitric acid can be transported by iron. The equation is:
When iron reacts with non-oxidizing acid (hydrochloric acid), sulfuric acid, sulfur, copper sulfate solution, etc., it loses two electrons and becomes +2 valence; when reacting with nitric acid, it depends on the ratio of the amount of the substance and the concentration of nitric acid (the following concentrated represents the concentration), dilute stands for lean, excess stands for excess).
Example: Displacement reaction between iron and copper sulfate solution:
(Principle of Wet Copper Smelting) This experiment shows that the metal activity of iron is stronger than that of copper.
(Reaction at room temperature for etching copper plates)
(The reason why Fe 3+and I -cannot coexist)
(Iron generally shows the essence of +2 price in replacement)
Example: The reaction between iron and chlorine:
Iron and chlorine react violently when ignited, and a large amount of brown-red smoke (FeCl 3 small particles) is reacted with Cl 2 and Br 2 to be oxidized to Fe 3+and is reacted with 12 to be oxidized to Fe 2+. The equation is:
(High temperature means high temperature) (Displacement reaction)
Iron can also be directly combined with sulfur, phosphorus, silicon, and carbon. Iron and nitrogen cannot be directly combined, but react with ammonia to form iron nitride Fe2N.
The divalent iron ion is light green and is easily oxidized to ferric ion in an alkaline solution. The color of the ferric ion changes from yellow to orange to brown as the degree of hydrolysis increases. Pure ferric iron ions are lavender. Both divalent and trivalent irons are susceptible to formation of stable coordination compounds with inorganic or organic ligands, such as Phen as pheniramine, with a coordination number of usually 6. Zero-valent iron can also form various carbonyl irons with carbon monoxide, such as Fe (CO) 5, Fe 2(CO) 9, Fe 3(CO) 12. The carbonyl iron is volatile and the vapor is highly toxic. Iron also has a +4, +5, +6 valence state, but only +6 valence (FeO 42-) in aqueous solution.
M — M+ 759.3
M+ — M2+ 1561
M2+ — M3+ 2957
M3+ — M4+ 5290
M4+ — M5+ 7240
M5+ — M6+ 9600
M6+ — M7+ 12100
M7+ — M8+ 14575
M8+ — M9+ 22678
M9+ — M10+ 25290
Among all nuclei, iron 56 nucleus is the most stable, and its average binding energy is the largest. Therefore, in the periodic table, elements that are lighter than iron 56 fuses to release energy, and fission than iron 56 release energy, only iron. 56. Both fusion and fission absorb energy and require very harsh conditions. This is why massive stars collapse into neutron stars or black holes when the core becomes iron.
The preparation of elemental iron is generally carried out by smelting. Using hematite (Fe 2O 3 ) or magnetite (Fe 3O 4) as raw material, reacting with coke and cosolvent in a smelting furnace, coke combustion produces carbon dioxide (CO 2), and carbon dioxide is in contact with excess coke. Metal iron is formed by the formation of carbon monoxide (CO), carbon monoxide and iron oxide in the ore. Add CaCO 3 generated at high temperatures CaO is removed from the ore of SiO 2, generated CaSiO 3 (slag).
Step: (high temperature refers to high temperature)
(Hematite iron making)
(Magnetite iron making)
The laboratory usually uses carbon monoxide to reduce iron oxide to prepare a small amount of elemental iron.
- For pharmaceutical, pesticide, powder metallurgy, hot hydrogen generator, gel propellant, combustion active agent, catalyst, water cleaning adsorbent, sintering active agent, powder metallurgy products, various mechanical parts products, hard alloy Materials and so on.
- Pure iron is used to make iron cores for generators and motors, reduced iron powder for powder metallurgy, and steel for manufacturing machines and tools. In addition, iron and its compounds are also used in the manufacture of magnets, drugs, inks, pigments, abrasives and the like.
- Used as a reducing agent. For the preparation of iron salts. Also used to prepare electronic components.
- Used as a nutritional supplement (iron fortifier).
- Used as a filler for epoxy adhesive in adhesives to prepare to cast repair adhesive. Often used as a reducing agent. It has a wide range of uses in the electronics industry, powder metallurgy, and machinery industries. FHY80.23 is mainly used for oil-containing bearings. FHY100.25 is mainly used for medium and low-density mechanical parts. HFY100.27 is mainly used for high-density mechanical parts.
Iron and life
Iron is also an essential element in the body. There are about 4 to 5 grams of iron in the adult body, of which 72% are hemoglobin, 3% is myoglobin, 0.2 is in the form of other compounds, and the rest is reserve iron.
Reserve iron accounts for about 25% and is mainly stored in the liver, spleen and bone marrow in the form of ferritin. Adult intake is 10 to 15 mg. pregnant women need 30mg.
Within one month, women lose about twice as much iron as men, and copper, cobalt, manganese, and vitamin C are needed to absorb iron.
Need people: Women, especially pregnant women, need to supplement iron, but pay attention to women taking too much iron during pregnancy will cause iron poisoning in the fetus.
If you are taking anti-inflammatory drugs or taking aspirin every day, you will need to add iron. People who drink black tea or coffee regularly should note that drinking a lot of black tea and coffee can hinder the absorption of iron.
Iron can be used repeatedly in the metabolic process. In addition to intestinal secretion excretion and loss of skin and mucosal epithelial loss of a certain amount of iron (1 mg/day), there is almost no other way to lose.
Iron in food
There are two forms of iron in food:
Non-heme iron: mainly composed of trivalent iron combined with protein and organic acid to form a complex. This form of iron must be separated from the organic part and reduced to ferrous iron before it can be absorbed.
If there is more phytic acid or phosphoric acid in the diet, it will form an insoluble iron salt with iron, and the effect will be absorbed. Ascorbic acid and cysteine can reduce ferric iron to divalent iron, which is beneficial to the absorption of iron.
Iron (Fe) is a component of hemoglobin, myoglobin and many enzymes in the body. Heme iron is mainly found in animal products and is much better absorbed than non-heme iron. Non-heme iron accounts for more than 85% of the iron in the average diet.
However, it can increase the absorption of non-heme iron when it is ingested with animal protein and vitamins.
Iron requirements, iron metabolism, and iron deficiency anemia are discussed in Section 127, Anemia Caused by Lack of Red Blood Cells. The iron overweight disease is discussed in Section 127.
Lack: Iron deficiency can because anemia is the most common nutritional deficiency in the world. Some infants, adolescent girls, and pregnant women suffer from iron deficiency anemia due to insufficient iron intake. Anyone who loses blood can produce an iron deficiency. All iron-deficient people need iron supplements.
Poisoning: Excess iron is toxic and can cause vomiting, diarrhea and intestinal damage. When a person gives iron overdose or takes too long, or repeatedly receives blood transfusions, or has chronic alcoholism, iron can accumulate in the body. Iron overweight disease (hemochromatosis) is a potentially fatal but treatable hereditary disease that absorbs too much iron; it affects 1 million Americans.
Rumors: High iron content in spinach
In the past, people thought that the iron content in spinach was very high, but it was not.
One scientist, he discovered during research, found that the iron content of spinach was much smaller than the recorded value. So, he did a lot of trials, and this is still the result, he published an article. This article has sensationalized the whole society, and other scientists have experimented and found this result.
It turned out that the pastor used to misplace a decimal point when copying the results.
Iron in the human body
Iron is the hematopoietic element of the human body, and women have one more iron-discharging channel — menstruation, so iron supplementation.
The amount should be greater than the male. The daily intake of iron is 15 mg, which keeps the complexion rosy. The most abundant and best-absorbed iron is pig liver, pig blood, duck blood, soy products, sesame seeds, mushrooms, fungus, kelp, seaweed, longan and so on. In addition, the fortified soy sauce with iron and iron has a good iron-reinforcing effect.
Iron deficiency anemia is one of the four major nutritional deficiencies identified by the World Health Organization.
- In the 18th century, Menghini used magnets to adsorb particles in dry blood, noting that iron contained in the blood.
- In 1892, Bunge noticed that infants and young children were prone to iron deficiency.
- In 1928, Mackay first proved that iron deficiency was the cause of the prevalence of anemia in infants in East London. She also thought that providing iron-fortified milk powder could alleviate anemia.
- In 1932, Castle and colleagues confirmed that inorganic iron can be used for hemoglobin synthesis.
Iron is the key to oxygen loading in heme
The human body may cause iron deficiency due to uneven nutrition, trauma, and women’s physiological cycle. According to statistics, Chinese women have more than 60% iron deficiency, and vegetarian women are more than 70%.
- The ability to resist the invasion of pathogenic microorganisms is diminished.
- Reduce the rate of response of immune cells from rest-the battle.
- Reduces the activity of antioxidant biochemical enzymes.
- Production of the antibody is stopped or at a very slow rate.
In addition, B vitamins can also promote our appetite. However, it should be noted that folic acid and vitamin B12 are of little help in the treatment of iron deficiency anemia.
Copper can promote the absorption of iron. When copper is scarce, the iron absorbed by the small intestine is reduced, and the synthesis of hemoglobin is also reduced, which will directly lead to iron deficiency anemia in the human body.