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💏intro to chemistry review

H3PO3

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

Definition

H3PO3, also known as phosphorous acid, is a chemical compound that is important in the context of the occurrence, preparation, and properties of phosphorus. It is a triprotic acid with the molecular formula H3PO3, consisting of one phosphorus atom bonded to three hydrogen atoms and three oxygen atoms.

5 Must Know Facts For Your Next Test

  1. H3PO3 is a white, crystalline solid that is soluble in water and has a sour taste.
  2. It is a reducing agent and can be used as a food preservative and in the production of fertilizers and other chemicals.
  3. H3PO3 is produced by the hydrolysis of phosphorus trichloride (PCl3) or by the partial oxidation of white phosphorus (P4).
  4. The triprotic nature of H3PO3 means it can donate up to three protons, forming H2PO3-, HPO3^2-, and PO3^3- ions.
  5. H3PO3 is an important intermediate in the Castner-Kellner process, which is used to produce chlorine and sodium hydroxide.

Review Questions

  • Explain the occurrence of H3PO3 in the context of phosphorus.
    • H3PO3, or phosphorous acid, is an important compound in the context of the occurrence of phosphorus. Phosphorus is a naturally occurring element that is widely distributed in the Earth's crust, and H3PO3 can be produced through the hydrolysis of phosphorus trichloride (PCl3) or the partial oxidation of white phosphorus (P4). The occurrence of H3PO3 is significant because it is an intermediate in the production of various phosphorus-containing compounds, including fertilizers and other industrial chemicals.
  • Describe the preparation of H3PO3 and its relationship to the properties of phosphorus.
    • The preparation of H3PO3 is closely tied to the properties of phosphorus. As mentioned, H3PO3 can be produced by the hydrolysis of phosphorus trichloride (PCl3) or the partial oxidation of white phosphorus (P4). These preparation methods are important because they take advantage of the reactivity and oxidation-reduction properties of phosphorus. The triprotic nature of H3PO3, which allows it to donate up to three protons, is also a key property that influences its chemical behavior and applications.
  • Analyze the role of H3PO3 in the properties of phosphorus, and how it relates to the broader understanding of this element.
    • H3PO3 plays a significant role in the properties of phosphorus, both in terms of its chemical behavior and its practical applications. As an intermediate in the production of various phosphorus-containing compounds, H3PO3 helps to elucidate the versatility and reactivity of phosphorus. Its reducing agent properties, as well as its ability to form different ionic species, contribute to our understanding of phosphorus and its diverse range of uses, from food preservation to fertilizer production. Studying the properties of H3PO3 and its relationship to phosphorus can provide valuable insights into the broader characteristics and applications of this important element.