Name: lead; Lead

Element symbol Pb

Atomic number 82

Atomic weight 207.2

The external electron arrangement is 6s26p2, which is located in the group Ⅳ a of the sixth period. The atomic radius is 146 Pico meters, the radius of PB4 + is 84 Pico meters, the first ionization energy is 718.96 kJ / mol, the electronegativity is 1.8, and the main oxidation numbers are + 2, + 4. Silver gray lustrous heavy metals are easy to oxidize and lose luster in the air, become gray and dark, have soft quality, weak ductility and strong expansibility. Its density is 11.34g/cm3, melting point 327.5 ℃, boiling point 1740 ℃. It has strong resistance to radioactive penetration. Toxic. At room temperature, a layer of lead oxide or basic lead carbonate is easily formed on the surface of lead in air, which makes lead lose luster and prevents further oxidation. It is insoluble in water. It is easy to combine with halogen and sulfide to form PbCl4, PbI2, PbS, etc. The molten lead reacts with air to form lead oxide, and lead dioxide can be obtained by heating lead in pure oxygen. It reacts with hydrochloric acid to release hydrogen and form slightly soluble PbCl2, which covers the surface of lead and stops the reaction. It reacts with hot concentrated hydrochloric acid to form hpbcl3 and H2. It reacts with dilute sulfuric acid to release hydrogen and form insoluble PbSO4 coating, which stops the reaction. However, Pb (HSO4) 2 is formed from concentrated sulfuric acid which is easily soluble in heat and SO2 is released. Lead nitrate Pb (NO3) 2 can be formed by reaction with dilute nitric acid or concentrated nitric acid. In the presence of oxygen, it is soluble in organic acids such as acetic acid to form soluble lead salt. It reacts slowly with strong alkali solution to release hydrogen to form lead sulfite

Pb+2NaOH=Na2PbO3+H2↑

In the presence of oxygen, Pb (OH) 2 reacts with water to form insoluble Pb (OH) 2. Lead was discovered and applied as early as 3000 BC. The mass percentage in the crust is 0.0016%. It mainly exists in galena (PBS) and galena (PbCO3). It can be used as cathode protection layer of cable, storage battery, cast alloy, Babbitt alloy, metal structure and anti-X-ray radiation material. It is made by reducing lead oxide with coke.

Name: lead oxide; Lead oxide;  Amitabha monk; Lead monoxide

Molecular formula: PbO

Molecular weight 223.19

Properties: light yellow or earth yellow, tetragonal or orthorhombic crystals, or amorphous powder. The crystal density of tetragonal system is 9.53g/cm3, that of orthorhombic system is 3.0g/cm3, and that of amorphous powder is 9.2-9.5g/cm3. The melting point is 888 ℃. The boiling point is 1470 ℃. Insoluble in water and ethanol, soluble in nitric acid, acetic acid or warm lye. Carbon dioxide is gradually absorbed in the air. When it is heated to 300-500 ℃, it becomes Pb3O4, and when the temperature is higher, it becomes pb2o1. Toxic!

The application field is mainly used for manufacturing lead white and lead soap. It is used as raw material of lead salt plastic stabilizer, raw material of lead glass industry and intermediate raw material of lead salt industry. It is also used as flux for metallurgy, drying agent for paint and raw material for ceramics. A small amount of it is used in traditional Chinese medicine and battery industry, and in the manufacture of anti radiation rubber products.

The chemical formula is PbO. There are two variants: one is red tetragonal crystal, also known as mithushen; Melting point 886 ° C. Boiling point 1472 ° C. 53 g / cm3. The other is yellow orthorhombic crystal, also known as lead yellow; Melting point 886 ° C. Boiling point 1472 ° C. The density is 8.0 g / cm3. The transition point is 488.5 ° C. Below this temperature, the transformation is slow. Both are insoluble in water. Lead oxide can dissolve in acid to form lead (Ⅱ) salt; It is also slightly soluble in strong alkali solution to form lead (Ⅱ) salts. Under heating, PBO is easily reduced to metallic lead by hydrogen, carbon and carbon monoxide.

Name: lead dioxide; lead dioxide

Molecular formula: PbO2

Molecular weight 239.19

Lead peroxide

English Name: lead oxide; Lead peroxide

Properties dark brown, micro crystalline, heavy powder. It's an oxide of tetravalent lead, not a peroxide of divalent lead. 36g / cm3. It is insoluble in water and ethanol, slowly soluble in nitric acid and ammonium acetate, and rapidly soluble in hydrochloric acid, nitric acid and hydrogen peroxide. When heated to 290 ℃, it is easy to decompose and form oxygen and lead trioxide. Oxygen and lead tetroxide are formed at higher temperature. It is a strong oxidant. It is heated with strong alkali to form high plumbate. Toxic!

Used in the manufacture of dyes, matches, fireworks and synthetic rubber. It is also used in the manufacture of perchlorate and high voltage arrester. Used as a curing agent for vulcanized rubber such as solvent resistant polysulfide rubber. Lead dioxide electrode is a good anode material, which can replace platinum anode.

When PbO is heated, oxygen is released to form PbO 4 and PbO 1 at high temperature. It is soluble in hydrochloric acid to release chlorine, in dilute nitric acid containing hydrogen peroxide, oxalic acid or other reducing agents, in hot caustic solution, in alkali iodide solution to release iodine, and insoluble in water. The relative density was 9.38. Melting point 290 ℃ (decomposition). It is oxidable and can cause combustion by friction or impact with organic matter. Median lethal dose (guinea pig, intraperitoneal) was 220mg / kg. It's stimulating. It can be used as oxidant in analysis and industry to oxidize Mn (II) to Mn (VII). Lead dioxide is used to combine oxides of nitrogen and sulfur in the analysis of organic elements by burning method. Manufacturing brown black filter coloring glass and battery electrode.

Name: lead trioxide; dilead trioxide

Molecular formula: Pb2O3

Nature: reddish yellow or green brown powder. Insoluble in cold water or potassium hydroxide solution. It can be decomposed into lead dioxide and lead oxide by concentrated acid. When the temperature is about 370 ℃, oxygen is released, and lead oxide is left. When the temperature is about 530 ℃, lead oxide is left. It decomposes slowly in hot water. It can be prepared by dissolving lead oxide in sodium hydroxide and then ozonation. It is used to make other oxides of lead.

Name: lead sulfate; lead sulfate; plumbous sulphate

Molecular formula: PbSO4

Molecular weight: 303.30

Density: 6.2

Melting point: 1170 ℃

Character: white monoclinic or orthorhombic crystal.

Solubility: extremely insoluble in water, insoluble in ethanol, soluble in ammonia solution of concentrated sulfuric acid, alkali, ammonium acetate and ammonium tartrate.

Usage: used for making batteries and paints.

Preparation or source: prepared by the interaction of lead nitrate and sodium sulfate solution.

Note: toxic!

Category: inorganic salt

CAS 7446-14-2

It is white monoclinic or orthorhombic crystal. The relative density is 6.2. The melting point is 1170 ℃. Insoluble in water (0.00025g/100ml water at 25 ℃, 0.0056g/100ml water at 40 ℃), soluble in ammonium salt, slightly soluble in hot water, concentrated sulfuric acid, insoluble in acid. Toxic!

It is used in the manufacture of cobalt salt, pigment, catalyst and coating drier

Toxic lead and its compounds are toxic to all living things. It can change the nervous system, blood and blood vessels. The maximum allowable concentration of lead and its inorganic compounds is 0.01 mg / m3. The average concentration is 0.007mg/m3. Operators should wear masks. When the vapor concentration is high, use the filter type gas mask to supply fresh air. No eating or smoking in the workplace during working hours.

The packing, storage and transportation shall be packed in iron drums or wooden drums lined with polyethylene plastic bags, or in plastic woven bags lined with polyethylene plastic bags, with a net weight of 40kg and 50kg per barrel (bag). Store in a well ventilated and dry warehouse. Do not store and transport together with food. In case of fire, it can be put out with water or various fire extinguishers.

Name: lead carbonate; lead carbonate

Alias: lead white

Chemical formula: PbCO3

Relative molecular weight: 267.20

Chemical category: inorganic metal oxide

Type of control: no control

Storage: cool and ventilated

Appearance and character: white rhombic crystal.

Melting point (℃): 400 (decomposition)

Relative density (water = 1): 6.61

Molecular formula: PbCO3

Solubility: insoluble in water and alcohol, soluble in acetic acid, lower alcohol, nitric acid and lye.

chemical property

It decomposes into PbO 1 and CO2 at 315 ℃. When it is azeotropic with water, it gradually loses carbon dioxide and becomes basic salt.

Function and use

Used in paint and ceramic industry.

Precautions for use

Risk overview

Health hazards: lead and its compounds damage hematopoiesis, nervous system, digestive system and kidney. Occupational poisoning is mainly chronic. The main manifestations of nervous system are neurasthenia syndrome, peripheral neuropathy, and lead poisoning encephalopathy in severe cases. Explosion hazard: the product is non combustible and toxic.

First aid measures

Skin contact: take off contaminated clothes and rinse with plenty of flowing water. Eye contact: lift eyelids and wash with flowing water or normal saline. See a doctor. Inhalation: quickly leave the scene to fresh air. Keep respiratory tract unobstructed. If you have difficulty breathing, give oxygen. If breathing stops, give artificial respiration immediately. See a doctor. Ingestion: drink enough warm water to induce vomiting. See a doctor.

Fire fighting measures

Hazard characteristics: it cannot burn itself. In case of high thermal decomposition, high toxic smoke is released.

Harmful combustion products: carbon monoxide, carbon dioxide, lead oxide, lead.

Fire fighting method: move the container from the fire site to the open area as far as possible.

Fire extinguishing agents: fog water, foam, dry powder, carbon dioxide and sand. 1]

Leakage emergency treatment

Emergency treatment: isolate the contaminated area and restrict access. It is suggested that emergency treatment personnel should wear dust masks and anti-virus clothing. Do not touch the leakage directly.

Small amount of leakage: avoid dust, sweep up carefully and collect in dry, clean and covered containers.

Large amount of leakage: collect and recycle or transport to waste treatment site for disposal.

Handling and storage

Operation precautions: closed operation, local exhaust. Prevent dust from releasing into the air of the workshop. Operators must be specially trained and strictly abide by the operating procedures. It is suggested that the operators should wear self-priming filter dust mask, chemical safety protective glasses, anti poison penetration work clothes and latex gloves. Avoid dust. Avoid contact with oxidants and acids. Equipped with leakage emergency treatment equipment. Empty containers may contain harmful substances. Storage precautions: store in a cool and ventilated warehouse. Keep away from fire and heat source. Keep out of direct sunlight. The package is sealed. It should be stored separately from oxidants, acids and edible chemicals, and avoid mixed storage. The storage area should be equipped with suitable materials to contain the leakage.

preparation

There are lead ores in nature, which can also be made from lead nitrate or lead acetate solution plus sodium carbonate or ammonium carbonate solution. It can also be prepared by treating lead sulfate or lead chloride with sodium carbonate.

View reply      See more

Last：Role of phytic acid

Next：Properties of Fluoroantimonic Acid