The main difference between phosphoric acid and phosphorus acid is that phosphoric acid is a stronger acid and contains more oxygen atoms per phosphorus atom, while phosphorous acid is less acidic and has fewer oxygen atoms attached to phosphorus.
Phosphoric acid and phosphorous acid are two distinct chemical compounds with unique properties and applications. Both acids contain phosphorus (P) as a central element in their chemical structures.
Key Areas Covered
1. What is Phosphoric Acid
– Definition, Composition, Features
2. What is Phosphorus Acid
– Definition, Composition, Features
3. Similarities Between Phosphoric Acid and Phosphorus Acid
– Outline of Common Features
4. Difference Between Phosphoric Acid and Phosphorus Acid
– Comparison of Key Differences
Key Terms
H3PO3, H3PO4, Phosphoric Acid, Phosphorus Acid
What is Phosphoric Acid
Phosphoric acid is an inorganic acid characterized by its chemical structure, which consists of one central phosphorus (P) atom surrounded by four oxygen (O) atoms. Its chemical formula is H3PO4. Phosphoric acid is a triprotic acid, meaning it can donate three protons (H+) in an aqueous solution, leading to the formation of three dissociation constants (pKa values) corresponding to the successive loss of hydrogen ions. The pKa values for phosphoric acid are approximately 2.15, 7.20, and 12.35.
The unique property of phosphoric acid is its ability to form a series of phosphate salts by reacting with bases or metal ions. Moreover, these salts are essential components in various industries, including agriculture, food and beverages, and the production of detergents and fertilizers.
Figure 1: Phosphoric Acid
Phosphoric acid has numerous industrial applications, including its pivotal role in producing phosphate fertilizers. It is also extensively utilized in the food and beverage sector for acidification and pH control, imparting a tangy taste to carbonated drinks and contributing to various food products. Additionally, phosphoric acid serves as a critical component in phosphate fertilizers, crucial for enhancing crop yields and soil fertility by providing essential phosphorus to plants.
What is Phosphorous Acid
Phosphorous acid is an inorganic compound composed of one phosphorus (P) atom, three oxygen (O) atoms, and three hydrogen (H) atoms. Its chemical formula is H3PO3. Furthermore, the central phosphorus atom in phosphorous acid exhibits a +3 oxidation state, making it an essential compound for redox reactions.
Figure 2: Phosphorus Acid
Key properties of phosphorous acid include its crystalline appearance, high solubility in water, and its ability to form salts called phosphites when it reacts with bases or metals. These properties are instrumental in its diverse applications.
Phosphorous acid is a potent fungicide used to combat plant diseases caused by various fungal pathogens. It is particularly effective against oomycetes, a group of destructive plant pathogens. Phosphorous acid has been shown to stimulate the defense mechanisms of plants, making them more resistant to diseases. It also helps plants activate their natural defense responses. Phosphorous acid is a source of phosphorus, an essential nutrient for plant growth. Moreover, it is used to supplement soil and provide the necessary phosphorus for healthy plant development.
Similarities Between Phosphoric Acid and Phosphorous Acid
- Phosphoric acid and phosphorous acid contain phosphorus (P) as a central element in their chemical structures.
- Both acids are classified as acids due to their ability to release hydrogen ions (H+) in aqueous solutions.
Difference Between Phosphoric Acid and Phosphorous Acid
Definition
Phosphoric acid is an inorganic acid with the chemical formula H3PO4, whereas Phosphorous acid is an inorganic compound with the chemical formula H3PO3.
Chemical Composition
Phosphoric acid contains four oxygen atoms and three hydrogen atoms for each phosphorus atom in its chemical structure. Meanwhile, phosphorous acid contains three oxygen atoms and three hydrogen atoms for each phosphorus atom in its chemical structure.
Oxidation State of Phosphorus
Phosphorus in phosphoric acid has an oxidation state of +5, making it a fully oxidized form of phosphorus. In contrast, phosphorus in phosphorous acid has an oxidation state of +3, indicating a partially reduced form of phosphorus.
Acidity
Moreover, phosphoric acid is a stronger acid compared to phosphorous acid.
Uses
Phosphoric acid has various industrial applications, including the production of phosphate fertilizers, as an acidulant and pH control agent in the food and beverage industry, and in rust removal and cleaning products. Meanwhile, phosphorous acid is primarily used as a reducing agent in chemical processes, as a fungicide in agriculture, and in some niche applications in organic synthesis.
Conclusion
The main difference between phosphoric acid and phosphorus acid is that phosphoric acid is a stronger acid and contains more oxygen atoms per phosphorus atom, while phosphorous acid is less acidic and has fewer oxygen atoms attached to phosphorus.
Reference:
1. “Phosphoric acid.” Wikipedia. Wikipedia Foundation.
2. “Phosphorous acid.” Wikipedia. Wikipedia Foundation.
Image Courtesy:
1. “Phosphoric-acid-3D-balls” (Public Domain) via Commons Wikimedia
2. “Phosphonic-acid-3D-balls-A” By Ben Mills – Own work (Public Domain) via Commons Wikimedia
Leave a Reply