Phosphorus Pentoxide (P2O5)

What is Phosphorus Pentoxide?

Phosphorus Pentoxide is a chemical compound whose empirical formula is P2O5 and whose molecular formula is P4O10.

At ambient temperatures, this compound exists as a white solid that is crystalline in nature. Phosphorus pentoxide is an acid anhydride that is obtained from phosphoric acid. It is highly hygroscopic and is, therefore, used as a dehydrating agent and as a desiccant.

Table of Contents

Preparation of Phosphorus Pentoxide

P2O5 (or P4O10) can be prepared by burning elemental P4 (tetra-phosphorus) in an environment containing a sufficient amount of oxygen. The chemical reaction for the preparation of P2O5 is provided below.

P4 + 5O2 → P4O10

This compound is a source of pure phosphoric acid.

Structure of Phosphorus Pentoxide

The structure of a phosphorus pentoxide molecule is illustrated below.

Structure of Phosphorus Pentoxide

It can be noted that the P=O bond length in this compound is 143 picometers and the P-O bond length is 160 picometers.

Properties of Phosphorus Pentoxide

Physical Properties of Phosphorus Pentoxide

  • Phosphorus pentoxide is a white solid which does not have any distinct odour.
  • The chemical formula of this compound is P4O10. However, it is named after its empirical formula, which is P2O5.
  • The molar mass of phosphorus pentoxide corresponds to 283.9 g/mol.
  • The density of this solid is 2.39 g/cm3.
  • The melting point of this P2O5 is 613K. Its boiling point corresponds to 633K (however, it undergoes sublimation at this temperature).

Chemical Properties of Phosphorus Pentoxide

  • Phosphorus pentoxide undergoes violent hydrolysis when exposed to water. This reaction is highly exothermic.
  • This compound crystallizes in four different polymorphs.
  • It is highly corrosive and must, therefore, be kept away from metals.

Uses of Phosphorus Pentoxide

  • This compound is a very potent dehydrating agent (since it undergoes hydrolysis in an exothermic manner).
  • Phosphorus pentoxide is also used in some organic synthesis reactions. For example, it is used in the preparation of nitriles from primary amides.
  • It is a vital component of the Onodera reagent, which is widely used in the oxidation of alcohols.
  • This compound can also be used to convert certain mineral acids into their anhydrides. For example, N2O5 can be prepared from HNO3 with the help of P2O5.


Frequently Asked Questions – FAQs

Q1

Is P2O5 an acid?

Phosphorus pentoxide is an acidic oxide and it is used as a desiccating and dehydrating agent because it is an anhydride of phosphoric acid.

Q2

Is P2O5 a phosphate?

Phosphorus pentoxide is a chemical compound with molecular formula P4O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydrating agent.

Q3

How many moles are in P2O5?

P2O5 is the empirical formula for the polymorph of P4O10. 1 mole is equal to 1 mole P2O5, or 141.944522 grams. This conversion is based on the molar mass ratio for the two compounds. P2O5 is named diphosphorus pentaoxide.

Q4

Is P2O5 a neutral oxide?

Phosphorus pentoxide has a very high oxidation state. So the above oxide is acidic in nature. N2O is a neutral oxide. It neither reacts with acid nor base.

Q5

How do you identify a neutral oxide?

Neutral oxides show neither basic nor acidic properties and hence do not form salts when reacted with acids or bases, e.g., carbon monoxide (CO); nitrous oxide (N2O); nitric oxide (NO), etc., are neutral oxides.

To learn more about phosphorus pentoxide and other important compounds of phosphorus (such as the oxoacids of phosphorus), register with BYJU’S and download the mobile application on your smartphone.

Test your knowledge on phosphorus pentoxide p2o5

Comments

Leave a Comment

Your Mobile number and Email id will not be published.

*

*

close
close

Play

&

Win