What Is P4O10?

What Is P4O10? Phosphorous pentoxide is the common compound with a chemical formula P4O10 and the empirical formula is P2O5. An example of a covalent molecule, phosphorus pentoxide, consists of 4 phosphorous (P) atoms and ten oxygen (O) atoms. Diphosphorus pentoxide, phosphoric anhydride, and tetraphosphorus are these compounds’ names.

What Is P4O10?

Structure of P4O10

Phosphorus pentoxide (P4O10) exists in four crystalline forms referred to as polymorphs of phosphorus pentoxide. The most important form is metastable polymorph, having formula P4O10 that, is phosphorus pentoxide.

Name Details
Van der Waals forces
1 Force of attraction present in the polymorphs that keep the molecules together is the van der Waals force.
2 In contrast to the typical crystals, the crystal packing is not close, although it’s highly symmetrical.
3 The structure of P4O10 is related to the anhydrides of phosphorus acid (P4O6). 4
5 Its boiling point is at 423.0 °C, and if heated abruptly, sublimation can occur.
Phosphorus acid preparation
1 The phosphorus acid can be obtained by condensing the vapors of phosphorus pentoxide.
2 The resultant compound obtained after the condensation is a highly hygroscopic solid.
3 Other polymorphic forms are polymers, but in all polymers, phosphorus atoms are linked with oxygen atoms in a tetrahedral form.

Macromolecular Form

If the compound (P4O10) is heated in a closed tube for many hours and the molten form is maintained at an increased temperature that inhibits the cooling of the compound, the macromolecular structure is obtained.

1. Orthorhombic Form

This slightly stable orthorhombic form with a density of 2.7 g/cm3 and a melting temperature of 562.0°C then make layers and that layered form contains interrelated rings of P6O6 rings.

2. Stable Form

The stable form has a high density as compared to the metastable form. Moreover, it has an orthorhombic structure and a three-dimensional form with a density of 3.5 g/cm3. The rest of the polymorph has either glass or amorphous form; it can be made by melting any other form.

Properties of P4O10

Phosphorus pentoxide (P4O10) is a chemical compound that is a dehydrating agent and excessively corrosive. The general properties of phosphorus pentoxide (P4O10) have been tabulated below:

:one: Name Phosphorus pentoxide
:two: Another name Phosphorus oxide diphosphonate
:three: Molecular formula P4O10
:four: Empirical formula P2O5
:five: Melting point 613 K
:six: Boiling point 360 °C
:seven: Molecular weight 141.922 g/mole
:eight: Physical form Dry powder, deliquescent
:nine: Isotopes :x:
:keycap_ten:Density 2.4 g/cm3

How Can P4o10 Be Prepared?

Phosphorus pentoxide (P4O10) is synthesized by burning the phosphorus with enough oxygen. It generates the following chemical equation:

P4 + 5 O2 → P4O10

1. Thermal Process

During the 20th century, the P4O10 produced concentrated phosphoric acid by a thermal process. The P4O10 obtained by burning white phosphorus was dissolved in dilute phosphorus acid to produce concentrated acid.

What Is P4O10?

2. Wet Process

With the advent of time, as the filtration technology has advanced, modern processes are replacing the old ones. Wet-process phosphoric acid is now a trending product in which the initializing ingredient is white phosphorus.

3. Phosphoric Acid Dehydration

Although dehydration of the phosphoric acid can lead to phosphorus pentoxide, yet is impossible to perform and obtain P4O10 because the heating will induce boiling before the dehydration.

Phosphorus Pentoxide and Water

As far as the question is concerned about the reaction of P4O10 with water after the understanding that what is P4O10? Phosphorus pentoxide (P4O10) reacts vigorously with water and undergoes hydrolysis. This hydrolysis process generates heat and phosphoric acid.

1. Contact With the Body Surface

If the reaction between water and P4O10 occurs at the body surface, the generation of HCl and H2SO4 may cause skin corrosion. Signs and symptoms of P4O10 corrosion are:

  • Extreme irritation.
  • Skin redness.
  • Severe burns and pain.

2. Inhalation of P4O10

A person who inhales phosphorus pentoxide (P4O10) can severely damage the mucous membrane and respiratory pathway. Signs and symptoms of this damage include an irritated nose and throat and majorly forced respiration.

Inhalation of phosphorus pentoxide may lead to pulmonary edema requiring immediate emergency treatment.

Periodic Table of Elements

3. Ingestion of P4O10

As phosphorus pentoxide is highly corrosive when it comes in contact with moisture either on the external body surface or internal. It leaves a burning effect on the mucosa of the digestive tract with serious signs and symptoms. Signs and symptoms of corrosion by phosphorus pentoxide may involve the following:

List Symptoms
1 Pain in the throat
2 Severe body pain
3 Nausea, vomiting, and diarrhea
4 Brownish and yellowish marks around the mouth
5 Macroglossia (swollen tongue) leading to difficult breathing
6 Chemical-induced pneumonia if aspired to lungs
7 May lead to death

4. Reactions of P4O10 to Eyes

Vapors and powdered particles of phosphorus pentoxide impart corrosive reactions to the eyes if they come in contact. It may burn or permanently damage the eyes.

5. Long-Term Exposure to P4O10

If phosphorus pentoxide is ingested or inhaled for longer durations, it may cause irreversible damage to internal systems due to its corrosive nature. It is referred to as phosphate poisoning and can cause the following abnormalities:

  • Hepatic injury

  • Renal injury

  • Hematic disorders

  • Heart problems

  • Abnormalities of the cavity, including jaws and teeth

In short :writing_hand:
Phosphorus pentoxide (P4O10) is a chemical compound used as a dehydrating agent. It is corrosive when it comes in contact with water and damages the surface and mucus membranes if inhaled, touched, or ingested.

P4o10 Ionic or Covalent?

To understand whether phosphorus pentoxide is ionic or covalent, we must look into the bonds the atoms are making with each other and the chemical nature of elements present in the compound.

As phosphorus and oxygen are both non-metallic elements, covalent bonds bind together. Hence it is obvious that phosphorus pentoxide has a covalent nature.

Moreover, upon hydrolysis, no ionic specie is generated, which is another indication of the covalent nature of phosphorus pentoxide.

Uses of Phosphorus Pentoxide

Phosphorus pentoxide (P4O10) is mainly and vastly used for drying as it reacts with water molecules and produces phosphoric acid with a lot of heat production.

1. Dehydrating Agent

It is used as granules to be used as a dehydrating agent. The exothermic nature of phosphorus pentoxide (P4O10) while reacting with water or moisture is its real capability to act as a dehydrating agent. Reaction with water can be given as:

P4O10 + 6 H2O → 4 H3PO4 (–177 kJ)

  • While the minus sign shows that the reaction is exothermic, and the value 177 kJ indicates the amount of heat released during the reaction.

  • Phosphoric acid produced as a product of hydrolysis is also a hygroscopic compound that further absorbs moisture.

  • Dehydrating capacity is less because of the formation of a protective coating that hinders further reaction.

For example

Dehydration of amide compounds to produce nitriles is performed by phosphorus pentoxide. Other uses of phosphorus pentoxide are listed below:

2. Acts as Initiating Material

Phosphorus esters are utilized as surfactants, and extraction reactions are prepared using phosphorus pentoxide as the starting material.

Chemistry Lab Experiment

3. P4O10 as a Synthetic Agent

Phosphorus pentoxide (P4O10) is used as a synthetic agent for several pharmaceutical agents and pesticide compounds.

4. Synthesis of Glass

One of the important uses of phosphorus pentoxide (P4O10) is that it is used in manufacturing optical and heat-resistant glass.

Summary :writing_hand:
Phosphorus pentoxide is the dehydrating compound and has a corrosive nature when it undergoes hydrolysis. It is used as a drying agent, starting material in various reactions, and glass synthesis.

Why is Phosphorus Pentoxide Named So?

P4O10 is the molecular formula of the substance in question. Changing it to an empirical formula is one way to make it easier to understand.

A molecular formula expresses the total number of molecules forming the compound, while the empirical formula is the simplest whole-number ratio of atoms in a compound.

  • The compound’s name is mostly inferred from its empirical formula, and the same is in the case of phosphorus pentoxide.

  • There are five oxygen atoms in the empirical formula of phosphorus pentoxide hence the name “pentoxide.”

Hazards of P4O10

Here are the following hazards of P4O10 are given below in the table.

Number Hazards
1 After discussing what P4O10 is, now it’s time to talk about its hazards.
2 Phosphorus pentoxide (P4O10) is not combustible by itself.
3 It undergoes a strong reaction when it comes in contact with water, moisture, or other water-containing agents such as cotton.
4 This reaction generates a lot of heat and hence an exothermic reaction.
5 If the reactions occur in the body tissues when it comes in contact with skin, they can cause skin burns and damage to eyes and mucous membranes.

Medical kit for P4O10 hazards

Frequently Asked Questions - FAQs

The chemical study is such a large topic that many questions pop into one’s mind when it’s concerned about phosphorus pentoxide. Some of them have been answered below:

1 - Why Is P4o10 Phosphorus Pentoxide?

Phosphorus pentoxide is the dehydrating agent with a molecular formula of P4O10, simplified to generate the empirical formula P2O5. Mostly, the name of a compound is inferred from its empirical formula, and the empirical formula of phosphorus pentoxide is P2O5. It is the reason for giving pentoxide the name phosphorus.

2 - Is P4o10 Acidic or Basic?

Phosphoric pentoxide P4O10 is acidic. To elaborate on what P4O10 is, it is a chemical compound with a large dehydration capability. Another unique property of phosphorus pentoxide is its corrosive nature. When phosphorus pentoxide P4O10 undergoes hydrolysis, it generates phosphoric acid and causes the corrosion of body tissues. Moreover, it reacts vigorously with bases, indicating the acidic nature of P4O10.

3 - How Is P4o10 Formed?

Following are the steps to form the P4O10.

  • Phosphorus pentoxide (P4O10) is synthesized by burning phosphorus in an excess amount of oxygen. It’s a white-colored, crystalline powder used vastly as a dehydrating agent.

  • P4O10 is obtained when water is eliminated from H3PO4 and undergoes hydrolysis when it comes in contact with water. This hydrolysis generates a lot of heat and phosphoric acid.

  • Phosphoric acid is also hygroscopic and absorbs remaining moisture.

4 - What Happens When Phosphorus Reacts with Oxygen?

Phosphorus undergoes a reaction with molecular oxygen and generally produces two types of oxides. Oxide production depends upon the availability of oxygen. When oxygen is present in a limited amount, the oxide produced is P4O6. When oxygen is present in ample amounts, P4O10 is generated, named phosphorus pentoxide P4O10.

5 - Why Is Phosphorus Called Devil’s Element?

Brand, the discoverer of phosphorus, discovered it as a white powder that undergoes a reaction with oxygen in the air. This reaction produces a greenish-white colored light. Some may think that the emission or production of that light is due to the Process of phosphorescence, but it can’t be glowing.

6 - What Makes P2o5 and P4o10 Different from One Another?

If it helps, P2O5 and P4O10 are essentially the same substance in various forms. The solid with the specific chemical formula P4O10 may be directly condensed from the gas phase, typically P4O10.

7 - Why Does Phosphorus Form P4o10?

You may be aware that when white phosphorus P4 combines with air, P4O10 is created. The P4-tetrahedron has lesser bond angles (60°) than what would be predicted from a head-on bond formation of three p-type orbitals (90°), which is the cause of this.

8 - Is P4o10 Organic or Inorganic?

Phosphorus pentoxide is used in organic chemistry to dehydrate organic compounds, such as turning amides into nitriles, an important class of organic molecules utilized in lab processes and rubber production.

9 - Are Phosphates Phosphorus?

The mineral phosphorus is present in the electrically charged particle known as phosphate. Together with the mineral calcium, phosphorus helps to create strong bones and teeth.

10 - Are Eggs High in Phosphorus?

Although they are a fantastic source of protein, big eggs also include 95 mg of phosphorus. Take off the yolk; each egg white contains just 5 mg phosphorus.


What is P4O10? It is a common question related to chemistry. P4O10 is known as phosphorus pentoxide, and its name is derived from its empirical formula, P2O5.
Phosphorus pentoxide P4O10 is a strong dehydrating agent and a desiccant in the granular form. Being highly corrosive, phosphorus pentoxide P4O10 comes in contact with the water; an exothermic reaction occurs with the generation of heat and phosphoric acid.

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This page was last updated on 11 October 2022 by Muhammad Zahid