Phosphorus pentoxide（phosphorus pentoxide）, the chemical formula is PtwoOfive, also known as phosphoric anhydride, anhydrous phosphoric acid, phosphorus pentoxide.It's pure whitepowderIf the purity is insufficient, it is yellow powder.It has a special pungent smell.[8]
Phosphorus pentoxide has strongcorrosiveandtoxicity, which may cause serious irritation orChemical burn。Excessive ingestion or inhalation may lead to phosphorus poisoning, with symptoms including nausea, vomiting, diarrhea, headache, dyspnea, and even death in serious cases.Phosphorus pentoxide is often used asdesiccantandDehydrating agentIt is also used to manufacture phosphoric acidpesticides、phosphateMain materials of.[1-2][20]
The chemical formula of phosphorus pentoxide is PtwoOfiveIt is composed of four phosphorus oxygen tetrahedrons.These tetrahedrons are connected by sharing oxygen atoms to form a fused ring structure.[4]
Phosphorus pentoxide has three different structures: h type, o type and o 'type.[5]
Type h PfourOten(The structure is shown in Figure 1.1)Is determined by the discrete PfourOtenHexagonal structure formed by molecules.Each phosphorus atom forms four POs with four oxygen atomsfourThe tetrahedron then connects four phosphorus atoms through a bond bridge formed by six oxygen atoms. The connection between phosphorus atoms and oxygen atoms is similar to the crystal structure of diamonds.[5]
O type P2O5(The structure is shown in Figure 1.2)With diagonal square structure, each POfourThree corners of the tetrahedron are connected with the adjacent POfourShare and spiral along the c-axis.Each phosphorus atom is connected to three oxygen atoms and one phosphorus atom, and each oxygen atom is connected to two phosphorus atoms.[5]
O 'type P2O5(The structure is shown in Figure 1.3)It is an infinite two-dimensional table and connected POfourThere are two faces parallel to each other.Each phosphorus atom is connected to three oxygen atoms and one phosphorus atom, and each oxygen atom is connected to two phosphorus atoms.[5]
In the three structures, oxygen atom always acts as POfourTherefore, the length of P-O bond of o type and o 'type is shorter than that of bond bridge of h type.Phosphorus pentoxide also has hygroscopicity when it is in solid state, which can absorb moisture in the air and cause deliquescence.[5]
Three different structures
Type h P4O10
O type P2O5
O 'type P2O5
Figure 1.1
Figure 1.2
Figure 1.3
The three structures of phosphorus pentoxide can be converted by heating treatment.Type h PtwoOfiveWhen heated at 400 ℃ for 2 hours, it can be converted into o-type PtwoOfive。And o 'type PtwoOfiveIt is made after heating at 450 ℃ for 24 hours.Under certain conditions, o type PtwoOfiveIt can also be converted to H-type PtwoOfive。[5-6]
Soluble in sulfuric acid, acetone and liquid ammonia.
Steam pressure
1mmHg@384° C (solid state)
reference material:[7][16][21]
chemical property
Phosphorus pentoxide is soluble in water and reacts with water to formMetaphosphate, followed byinorganpyrophosphateAnd finally forms orthophosphoric acid.
Reaction with cold water:
Reaction with hot water:
Phosphorus pentoxide has a strong affinity for water, and can even take combined water from many compounds, such as dehydration of nitric acid, sulfuric acid, etc.
Reaction with sulfuric acid:
Phosphorus pentoxide reacts with basic oxide to form phosphate.
Phosphorus pentoxide decomposes when heated or in contact with water and emits toxic and corrosive smoke.
Phosphorus pentoxide is highly corrosive.
reference material:[9][20][22]
Preparation method
Announce
edit
To prepare phosphorus pentoxide, phosphorus ore, coke scale and silica sand need to be mixed with appropriate amount of iron chips.After mixing evenly, it is put into the ore melting furnace.At high temperature, hot air of about 650 ℃ is introduced to fully burn white phosphorus.After a period of reaction, the combustion products will be captured and collected to obtain phosphorus pentoxide.During the process, the reaction conditions and temperature shall be controlled to ensure the quality and purity of the product.[10]
Burning white phosphorus in dry air to obtain phosphorus pentoxide is the most simple method.[9]
Preparation method of phosphorus pentoxide
PtwoOfiveIt is generated by white phosphorus burning under sufficient oxygen.[23]
White phosphorus burns in air
application area
Announce
edit
Phosphorus pentoxide is mainly used as a desiccant for gas and liquid, a dehydrating agent for organic synthesis, an antistatic agent for polyester resin, a refining agent for medicine and sugar, as well as a parent material for producing high-purity phosphoric acid, phosphate, phosphide and phosphate ester, and can also be used in the manufacture of phosphorus pentoxide sol and H-type aerosol.It is used to manufacture optical glass, ultraviolet transmitting glass, heat insulating glass, microcrystalline glass, opacified glass, etc., to improve the dispersion coefficient of glass and the ability of transmitting ultraviolet light.
The burning of white phosphorus bombs in the Palestinian Israeli conflict will also produce highly toxic phosphorus pentoxide smoke, which will corrode the respiratory tract if inhaled, and may lead to asphyxia and permanent respiratory system damage.Therefore, the international law system has strict restrictions on the use of white phosphorus bombs.[12]
Security matters
Announce
edit
Hazard characteristics
Phosphorus pentoxide is highly corrosive.When contacting with water, it will release a lot of heat and decompose, producing toxic and corrosive gases.These gases will cause harm to the human body, as well as irritation and injury to the skin and eyes.When phosphorus pentoxide contacts with organic substances, it may cause combustion and release more heat and toxic gases, which may cause fire, burns and other dangerous situations.[10][13]
The National Fire Protection Agency (NFPA) stipulates in Article 704 of the National Fire Protection Act that phosphorus pentoxide is a hazardous material and is applicable to systems that identify hazards associated with materials.The development of the system mainly considers the needs of the fire department, but it is valuable for anyone, including those who take chemistry laboratory courses, who need to deal with potentially dangerous materials.[25]
Phosphorus pentoxide is a first grade inorganic acid corrosive product with strong stimulation and corrosion effect.Its vapor and dust can stimulate the eyes, mouth mucosa and respiratory system of the human body, resulting in dyspnea, and even toxic pneumonia and pulmonary edema in serious cases.Long term exposure to phosphorus pentoxide may also cause chronic respiratory diseases.Phosphorus pentoxide also has obvious irritating and corrosive effects on human skin.The skin exposed to phosphorus pentoxide will suffer from pain, itching, redness, swelling and other symptoms, which may lead to skin ulcer and necrosis in serious cases.[3][14]
Phosphorus pentoxide sometimes contains free phosphorus.If excessive phosphorus is ingested or inhaled, phosphorus poisoning may result.The symptoms of phosphorus poisoning include nausea, vomiting, diarrhea, headache, dyspnea, and even death in severe cases.[3][14]
Emergency Management
Leakage disposal method
Isolate the leakage contaminated area, set up warning signs around it, and suggest emergency treatment personnel to wear gas masks and chemical protective clothing.Do not directly contact the leakage, do not make the leakage contact with combustible materials (wood, paper, oil, etc.), do not directly spray water on the leakage, and do not let water enter the packaging container.Carefully sweep it up, add a small amount of water, adjust it to neutral, and then put it into the waste water system.If there is a large amount of leakage, remove it under the guidance of technicians.[15]
Fire fighting methods
Extinguishing agent:Sand, dry powder.Do not use water.
If the substance or contaminated fluid enters the waterway, notify downstream users with potential water pollution, local health and fire officials and pollution control departments.Use atomized water to cool exposed containers beyond the safe explosion-proof distance.[15]
First aid measures
Skin contact: wipe off the poison with soft paper or cotton as soon as possible, and then soak it with 3% sodium bicarbonate solution.Then rinse thoroughly with water and seek medical advice.Remove and isolate contaminated clothing and shoes.For a small amount of skin contact, avoid expanding the spread area of the material.Wipe off the solidified molten substance on the skin under the guidance of the doctor.Keep the patient warm and quiet.Inhalation, ingestion or skin contact with the substance may cause delayed reaction.Ensure that medical personnel understand the personal protection knowledge related to this substance and pay attention to their own protection.[16]
Inhalation:Quickly leave the site to fresh air.Perform artificial respiration when necessary.Get medical attention.If breathing is difficult, give oxygen.If the patient ingests or inhales the substance, do not use mouth to mouth artificial respiration, use a small one-way valve respirator or other appropriate medical respirators.[16]
Ingestion:Rinse the mouth immediately and give milk or egg white to those who take it by mistake.Get medical attention.[16]
Storage and transportation
Store in a dry and clean warehouse.The relative humidity is kept below 75%.Keep away from kindling and heat sources.The package must be sealed to prevent moisture.It shall be stored separately from inflammables, combustibles, alkalis, etc.Mixed storage and transportation are not allowed.Pay attention to personal protection during sub packaging and handling operations.Load and unload gently during transportation to prevent damage to packaging and containers.It is not suitable for transportation in rainy days.Abandonment: refer to relevant national and local regulations before disposal.Use safe burial method for disposal.
Relevant cases:In September 2023, when the law enforcement personnel of Longyou County Emergency Management Bureau inspected a chemical company in Longyou, Zhejiang, they found that the company had put 2 tons of phosphorus pentoxide in the intermediate stock of raw materials, but did not stick the safety awareness card, safety technical instructions and safety labels of dangerous chemicals as required.This violates Article 78 (8) of the Regulations on the Safety Management of Hazardous Chemicals.Therefore, the Emergency Management Bureau of Longyou County fined the company 30000 yuan for its illegal acts.In addition, the on-site principal of the company, Mr. Shi, violated the provisions of Article 25 (5) of the Production Safety Law of the People's Republic of China due to his failure to timely investigate the hidden dangers of production safety accidents and perform his duties of production safety management.Therefore, Longyou County Emergency Management Bureau imposed an administrative penalty of 10000 yuan on Shi.[17]
