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💏intro to chemistry review

Phosphorus(V) Oxide

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Phosphorus(V) oxide, also known as phosphoric anhydride or diphosphorus pentoxide, is a chemical compound composed of phosphorus and oxygen. It is a key compound in the context of understanding the occurrence, preparation, and properties of phosphorus as outlined in Section 18.8 of the chemistry curriculum.

5 Must Know Facts For Your Next Test

  1. Phosphorus(V) oxide is a white, crystalline solid that is the anhydride of phosphoric acid.
  2. It is produced commercially by the combustion of white phosphorus in air or by the thermal decomposition of phosphates.
  3. Phosphorus(V) oxide is a powerful desiccant and dehydrating agent, capable of removing water from many organic and inorganic substances.
  4. When dissolved in water, phosphorus(V) oxide undergoes a highly exothermic reaction to form phosphoric acid, which has numerous industrial and agricultural applications.
  5. Due to its corrosive and hygroscopic nature, phosphorus(V) oxide must be handled with care and stored in airtight containers.

Review Questions

  • Describe the occurrence and preparation of phosphorus(V) oxide.
    • Phosphorus(V) oxide occurs naturally as a product of the combustion of phosphorus in air. It can also be prepared commercially by the thermal decomposition of phosphates, such as calcium phosphate. The reaction involves heating the phosphate compound to high temperatures, causing the release of phosphorus(V) oxide as a volatile product that can be collected and purified.
  • Explain the chemical properties and reactivity of phosphorus(V) oxide.
    • Phosphorus(V) oxide is a highly reactive and hygroscopic compound. It is a powerful desiccant, capable of removing water from many organic and inorganic substances. When dissolved in water, phosphorus(V) oxide undergoes a highly exothermic reaction to form phosphoric acid, $ ext{H}_{3} ext{PO}_{4}$. This reaction releases a significant amount of heat, making phosphorus(V) oxide a corrosive and potentially dangerous substance that must be handled with care.
  • Discuss the industrial and agricultural applications of phosphorus(V) oxide and its derived compounds.
    • Phosphorus(V) oxide and its derived compounds, such as phosphoric acid, have numerous industrial and agricultural applications. Phosphoric acid is used in the production of fertilizers, detergents, food additives, and various industrial chemicals. It is also a key component in the manufacture of phosphate-based fertilizers, which are essential for crop growth and soil fertility. Additionally, phosphorus(V) oxide and its derivatives find use in the production of flame retardants, ceramics, and as desiccants in various industrial processes.