Zinc Properties || What are the properties and uses of zinc?
Zinc is a chemical element, its chemical symbol is Zn, and its atomic number is 30. It is located in the fourth periodic table, group IIB in the periodic table of chemical elements. Zinc Properties are similar to aluminum.
Zinc is a light gray transition metal and the fourth “common” metal. In the modern industry, zinc is an irreplaceable battery and is a very important metal. In addition, zinc is also one of the essential trace elements in the human body and plays an extremely important role.
Zinc Metal
Zinc, its name “ zinc” comes from the Latin Zincum, which means “A thin layer of white “or” white deposit.” The chemical symbol is Zn, its atomic ordinal number is 30, the relative atomic mass of 65. Zinc is a white slightly blue silver metal, a density of 7.14 g/cc. The melting point is 419.5℃.
It is brittle at room temperature. It becomes soft at 100 ~ 150℃, it dries after 200℃. The chemical properties of zinc are lively. In the air at normal temperature, a thin layer forms a dense basic zinc carbonate film that prevents further oxidation. When the temperature reaches 225°C, zinc oxidizes violently.
Zinc is difficult to burn in air and emits a strong white light in oxygen. Zinc surface with a layer of zinc oxide, burning out white smoke, white smoke is the main component of zinc oxide, zinc barrier only combustion, the flame is formed pale refracted light. Zinc is easily soluble in acid, and it is also easy to replace gold, silver, copper, etc. from the solution.
The melting point of the zinc oxide film is high, but the melting point of metal zinc is very low. Therefore, when the zinc flakes are heated on an alcohol lamp, the zinc flakes are melted and softened, but they do not fall, it is because of the role of the oxide film. Zinc is mainly used in the fields of iron and steel, metallurgy, machinery, electrical, chemical, light industry, military, and medicine.
Regulatory Information: Zinc powder aliases zinc granules, high-purity zinc, arsenic-free zinc, etc. are explosive materials, and are regulated by the public security department in accordance with the “Dangerous Chemicals Safety Management Regulations”
Physical zinc Properties
Zinc is a blue-white metal. When the temperature reaches 225°C, zinc oxidation is intense. Zinc is easily soluble in acid, and it is also easy to replace gold, silver, copper, etc. from the solution. Zinc exists mostly in the sulfide state in nature. The main zinc-containing mineral is sphalerite. There are also small amounts of oxidized ore, such as siderite, such as siderite and heteropolar ore.
Common alloys containing zinc:
Tinplate — tin-plated sheet steel
Brass — alloys of zinc and copper
Which has long been used by ancient people? The production of brass was probably one of the earliest incidental discoveries in metallurgy.
Chemical Zinc Properties
The chemical properties of zinc are similar to aluminum so the chemical properties of zinc (amphoteric) can usually be inferred from the properties of aluminum.
① Elemental zinc can react with acid and alkali.
② Zinc oxide and zinc hydroxide are soluble in both acid and alkali.
Elemental zinc
2Zn + O2 ===== 2ZnO (1273K)
Zn + 2NaOH == Na2ZnO2 + H2 ↑
Zn + X2 === ZnX2 (X = F, Cl, Br, I) (under heating conditions)
3Zn + 2P ==== Zn3P2 (873K)
Zn + S === ZnS (under heating conditions)
Zn + 4NH3 + 2H2O ===== [Zn (NH3)4] (OH)2 + H2 ↑
Zn + 2HCl === ZnCl2 + H2 ↑
Zn + 2H2SO4 (concentrated) === ZnSO4 + SO2 ↑ + 2H2O
Zn + H2SO4 (lean) === ZnSO4 + H2 ↑
Zinc Hydroxide
Zn (OH) 2 + 2H + == Zn2+ + 2H2O
Zn (OH)2 + 2OH — == [Zn(OH)4]2-
A Zn(OH)2 + 4NH .3 H2O = (a Zn(NH2.3).4)2+ + 2OH — + 4H2O
Zn(OH)2 == ZnO + H2O
[Zn(NH3)4]2+ + 2OH — == Zn(OH)2 + 4NH3 ↑
Zinc Chloride
ZnO + 2HCl == ZnCl2 + H2O
ZnCl2 + 2H2O === Zn(OH)Cl + 2HCl (under heating conditions)
ZnCl2 + 2H2O = H2[ZnCl2(OH)2 ]
FeO + H2[ZnCl 2 (OH)2] == Fe [ZnCl 2 (OH)]2 + H2O
Zn + CuCl2 = ZnCl2 + Cu
Zinc Sulfide
2ZnO + 2S == 2ZnS + O 2 ↑
Zn 2+ + (NH 4 ) S == ZnS + 2NH 4 +
ZnSO 4 + BaS == ZnS + BaSO 4
Zn 2+ + H 2 S == ZnS + 2H +
Zinc Nitrate
1) Zn + 4HNO 3 (concentrated) == Zn (NO 3 ) 2 + NO 2 ↑ + 2H 2 O
2) 3Zn + 8HNO 3 ( richer ) == 3Zn (NO 3 ) 2 + 2NO ↑ + 4H 2 O
3) 4Zn + 10HNO 3 (dilute) == 4Zn (NO 3 ) 2 + N 2 O ↑ + 5H 2 O
4) 4Zn + 10HNO 3 (very dilute) == 4Zn (NO 3 ) 2 + NH 4 NO 3 + 3H 2 O
Zinc Complex
(a) [Zn (NH 3 ) 4 ] 2+
(b) [Zn (CN) 4 ] 2- [1]
Zinc Preparation
Calcining zinc ore or sphalerite in the air to obtain zinc oxide and then reducing it with carbon (lower purity).
Or zinc oxide and coke are mixed and heated in a blast furnace to cause 1373K ~ 1573K so that the zinc is distilled out (purity is about 98%).
Or with sulfate leaching into zinc sulfate after by controlling the PH, zinc sulfate and zinc dissolved iron impurities arsenic, antimony, hydrolysis enter into leaching residue precipitate, the filtrate was added zinc powder to remove impurities such as cadmium in copper, and then electrolysis The zinc was deposited, and the latter produced zinc with a higher purity.
Product Usage
About half of all zinc consumption in the world is used for galvanizing, about 10% for brass and bronze, less than 10% for zinc-based alloys, about 7.5% for chemicals, and about 13% for dry batteries Appears in the form of zinc cake and zinc plate.
The International Lead and Zinc Research Group predict that global zinc consumption in 2004 will increase by 4.8% from 9.85 million tons in 2003, and will increase by 4.3% in 2005. It is estimated that China will account for a quarter of the world’s total zinc consumption in 2005.
Its consumption growth is partly due to the increase in the amount of galvanized steel. In contrast, the United States may account for only one-tenth of global zinc demand.
Industry use
(1)Galvanized have excellent atmospheric corrosion resistance, easy to generate a protective film surface at room temperature, so the maximum use of zinc for plating zinc industry. It is mainly used for the surface coating of steel and steel structural parts (such as galvanized sheet) and is widely used in automobiles, construction, ships, light industry, and other industries.
After the 21st century, western countries began to try to use the zinc alloy plate as roof covering material directly. Its service life can be as long as 120–140 years, and it can be recycled. The service life of galvanized iron plate is generally 5–10 years. After the 21st century, the amount of hot-dip galvanizing of steel strips has increased significantly.
Plating zinc is also used, but this method is generally used for a thin coating of different surface finishes. The use of zinc-containing coatings is another method of coating for objects that are in continuous contact with water, such as large steel components used in ships, bridges and offshore oil and gas derricks, they only need to be connected to large zinc blocks. Protected, but zinc blocks need to be replaced regularly.
Zinc Alloy
(2) Zinc alloys are used in automobile manufacturing and machinery industries. Zinc has suitable mechanical properties. The strength and hardness of zinc itself are not high, but after adding alloy elements such as aluminum and copper, its strength and hardness are greatly improved.
It is like the emergence of zinc-copper-titanium alloys, and its comprehensive mechanical properties have approached or reached that of aluminum alloys and yellow alloys. The level of copper and gray cast iron, its creep resistance is also greatly improved. Therefore, zinc copper titanium alloy has been widely used in the production of small hardware.
Mainly die-castings, used in the production of parts for automobiles, construction, some electrical equipment, household appliances, toys, etc. Many zinc alloys have excellent processing performance, and the pass processing rate can reach 60% -80%.
Excellent medium-pressure performance, deep drawing, and self-lubrication, which prolongs the life of the mold. It can be welded by brazing or resistance welding or arc welding (in helium).
The surface can be plated and painted. Good cutting performance. Superior under certain conditions. Generally used in machinery manufacturing. Zinc plate with small amounts of elements such as lead and cadmium can be made zinc-manganese dry battery anode, a zinc plate printing, etching powdered photographic plate making offset printing plates and the like.
Zinc Batteries
(3) Zinc can be used to make batteries. For example zinc manganese batteries and zinc-air batteries.
Zinc-manganese battery: Zinc, as the negative electrode active material, also serves as the battery container and negative electrode current collector and is the main material that determines the battery storage performance. Small amounts of cadmium and lead are contained in zinc flakes.
Cadmium can increase the strength of zinc, and lead can improve the ductility of zinc. Both cadmium and lead can increase the overpotential of hydrogen on the zinc electrode, reduce the self-discharge of the zinc electrode, and slow the corrosion of zinc flakes and the release of hydrogen.
If zinc flakes contain Cu, Fe, Ni, etc., the overpotential of H 2 on the zinc electrode will be reduced, and the self-discharge of the battery during storage will be accelerated. Therefore, these harmful impurities must be strictly controlled.
Zinc-air battery: Zinc-air battery, also called a zinc-oxygen battery, is a kind of metal-air battery. The theoretical value of the specific energy of a zinc-air battery is 1350W · h/kg. The latest battery has a specific energy of 230Wh / kg, which is almost 8 times that of lead-acid batteries. It can be seen that the development space of zinc-air batteries is very large.
Zinc-air batteries are generally “mechanically charged” by replacing the zinc electrode. The electrode replacement time can be completed in minutes. With the new zinc electrode, the “charging” time is extremely short and very convenient.
What are zinc batteries used for?
If such batteries are developed, the construction of social security facilities such as charging stations is eliminated. Zinc electrodes can be purchased at supermarkets, battery operation points, auto parts stores, etc., which is very beneficial to popularize this battery-electric vehicle.
This battery has a small size, a large charge capacity, and a small mass, and can work normally in a wide temperature range without corrosion, and it is safe and reliable to work.
However, the zinc electrode consumes more energy in the electrolytic reduction process. Each ton of zinc oxide needs 2500 kWh of electricity to reduce it to zinc, so it is more expensive to use it in electric vehicles. The charge capacity of the test battery is only 5 times that of the lead-acid battery, which is not ideal.
But five times the charge of lead-acid batteries have attracted worldwide attention. The United States, Mexico, Singapore, and some European countries have already tried it on postal cars, buses, and motorcycles. It is also a promising electric vehicle.
In addition, zinc has good resistance to electromagnetic fields. The electrical conductivity of zinc is 29% off standard electrical copper. The zinc plate is very effective shielding material. At the same time, because zinc is non-magnetic, it is suitable as a material for instrument parts and instrument housings and coins.
Other metal collisions will not cause sparks, suitable for underground explosion-proof equipment. Widely used in rubber, coating, enamel, medicine, printing, fiber and other industries. Zinc has suitable chemical properties. Zinc can interact with NH4CI and emit H + positive ions.
Zinc- manganese dioxide batteries use this feature of zinc. The zinc alloy is used as the battery casing, which is not only a container for the battery electrolyte but also participates in the battery reaction to form the anode of the battery. Its performance is also widely used in the pharmaceutical industry.
Zinc can react with acids or strong bases to give off hydrogen. Zinc fertilizer has a role in promoting plant cell respiration, carbohydrate metabolism and the like. Zinc powder, zinc sulfide, lithopone, zinc chrome yellow pigments can be used. Oxide, zinc may also be used in medicine, rubber, paint and other industries.
Safety Measures
1. Store in a cool, dry place, away from fire and heat sources.
2. Separated from oxidants, amines, sulfur, phosphorus, acids, and alkalis.
3. Fire extinguishing: dry powder, dry sand. Disable water and foam.
Zinc and Health
The physiological function of zinc
Maintain Normal appetite
Zinc deficiency can lead to decreased taste, anorexia, partial eclipse, and even eclipse.
Enhance human immunity
Zinc is a nutrient for the development of the thymus of the immune organs. Only sufficient zinc can effectively ensure the development of the thymus, properly differentiate T lymphocytes, and promote cellular immune function.
Zinc can help growth and development, intellectual development, and improve immunity. Lack of zinc can seriously affect our body, especially growth and development. Therefore, adequate zinc supplementation is necessary for growth and development and intellectual development. In addition to eating a balanced diet, don’t forget to supplement your nutrition.
Symptoms of zinc deficiency
child
Taste disorders: anorexia, partial eating or unusual eating.
Skin disorders: susceptible to oral ulcers, damaged wounds are not easy to heal, adolescent acne, etc.
Poor growth and development: short and thin.
Decreased immunity, frequent colds, and fevers.
Pregnant woman
Increased pregnancy response: acidophilus, worse vomiting.
Intrauterine fetal growth retardation: leading to premature and low birth weight infants.
Increased birth complications: prolonged labor, miscarriage.
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Originally published at https://www.chemistrypage.in on February 1, 2020.
