Orthophosphoric Acid vs. Phosphoric Acid

Attribute	Orthophosphoric Acid	Phosphoric Acid
Chemical Formula	H3PO4	H3PO4
Molar Mass	97.994 g/mol	97.994 g/mol
Common Name	Orthophosphoric Acid	Phosphoric Acid
IUPAC Name	Phosphonic Acid	Phosphoric Acid
Appearance	Colorless liquid	Colorless liquid
Odor	Odorless	Odorless
Solubility	Soluble in water	Soluble in water
pH	Highly acidic (pH < 1)	Acidic (pH < 7)
Uses	Food and beverage industry, fertilizers, detergents	Food and beverage industry, fertilizers, detergents

Introduction

Orthophosphoric acid and phosphoric acid are two terms often used interchangeably to refer to the same compound, H₃PO₄. However, there are subtle differences between the two that are worth exploring. In this article, we will delve into the attributes of orthophosphoric acid and phosphoric acid, highlighting their chemical properties, applications, and potential health effects.

Chemical Properties

Orthophosphoric acid and phosphoric acid are both derived from phosphorus, a chemical element with the symbol P and atomic number 15. They are classified as oxyacids, which are acids that contain oxygen. The chemical formula for both compounds is H₃PO₄, indicating that they consist of three hydrogen atoms, one phosphorus atom, and four oxygen atoms.

Orthophosphoric acid is the most basic form of phosphoric acid, often referred to as phosphoric acid itself. It is a colorless, odorless, and viscous liquid that is highly soluble in water. On the other hand, phosphoric acid is a broader term that encompasses various forms of phosphoric acid, including orthophosphoric acid. It can exist in different states of ionization, such as dihydrogen phosphate (H₂PO₄^-) and hydrogen phosphate (HPO₄^2-), depending on the pH of the solution.

Applications

Both orthophosphoric acid and phosphoric acid find numerous applications across various industries.

Orthophosphoric Acid:

• Food and Beverage Industry: Orthophosphoric acid is commonly used as an acidulant and flavor enhancer in the production of carbonated beverages, jams, jellies, and processed meats. It helps regulate the pH, enhances the tartness, and acts as a preservative.
• Fertilizer Industry: Orthophosphoric acid is a key ingredient in the production of fertilizers. It provides essential phosphorus to plants, promoting healthy root development and overall growth.
• Pharmaceutical Industry: Orthophosphoric acid is utilized in the manufacturing of certain medications, including antibiotics and antacids. It serves as a pH regulator and aids in the formulation of stable drug compounds.
• Water Treatment: Orthophosphoric acid is employed in water treatment processes to prevent the formation of scale and corrosion in pipes and equipment. It helps maintain the water's pH balance and prevents the growth of harmful bacteria.

Phosphoric Acid:

• Industrial Cleaning: Phosphoric acid is widely used as a cleaning agent due to its ability to remove rust, mineral deposits, and stains from various surfaces. It is particularly effective in cleaning metals and concrete.
• Manufacturing: Phosphoric acid is utilized in the production of detergents, metal coatings, and flame retardants. It acts as a catalyst in certain chemical reactions and aids in the synthesis of various compounds.
• Electronics Industry: Phosphoric acid is employed in the etching process of printed circuit boards (PCBs). It helps remove unwanted copper from the board's surface, creating the desired circuit pattern.
• Dentistry: Phosphoric acid is used in dentistry as an etching agent to prepare teeth for bonding procedures. It creates micro-pores on the tooth surface, enhancing the adhesion of dental materials.

Health Effects

While both orthophosphoric acid and phosphoric acid are generally recognized as safe for consumption in small quantities, excessive exposure or ingestion can have adverse health effects.

Orthophosphoric Acid:

Orthophosphoric acid is considered relatively safe when used in food and beverage applications within approved limits. However, prolonged and excessive consumption may lead to dental erosion and mineral imbalances in the body. It is important to note that the concentration and frequency of exposure play a significant role in determining the potential health risks.

Phosphoric Acid:

Phosphoric acid, particularly in its concentrated form, can be corrosive and harmful if not handled properly. Direct contact with the skin or eyes may cause severe burns. Ingestion of concentrated phosphoric acid can lead to internal burns, abdominal pain, and digestive issues. It is crucial to handle and store phosphoric acid with caution, following appropriate safety protocols.

Conclusion

Orthophosphoric acid and phosphoric acid, while often used interchangeably, have distinct characteristics and applications. Orthophosphoric acid is the most basic form of phosphoric acid, serving as an acidulant in the food and beverage industry, a key component in fertilizers, and a pH regulator in water treatment. Phosphoric acid, on the other hand, encompasses various forms and finds applications in industrial cleaning, manufacturing, electronics, and dentistry. It is important to be aware of the potential health effects associated with both compounds and handle them with care. Understanding the differences between orthophosphoric acid and phosphoric acid allows for informed decision-making in various industries and ensures the safe use of these chemicals.