Phosphoric acid introduction

Phosphoric acid, with the chemical formula H₃PO₄, is a common inorganic acid widely used in industry, food, agriculture and other fields.

Basic properties:

• Appearance: Pure phosphoric acid is a colorless transparent crystal or viscous liquid, and most commercial products are 85% aqueous solutions.
• Solubility: Easily soluble in water and can be miscible with water in any proportion.
• Acidity: It is a medium-strong acid and corrosive.
• Boiling point: The boiling point of pure phosphoric acid is 158°C (decomposition), and the boiling point of 85% aqueous solution is about 120°C.

Main Application:

1. Food industry:
   As an acidity regulator, preservative and nutritional supplement, used in beverages, dairy products, etc.
   Used in the manufacture of food-grade phosphates (such as sodium dihydrogen phosphate, disodium hydrogen phosphate, etc.).
2. Agriculture:
   Used in the production of phosphate fertilizers (such as superphosphate, ammonium phosphate, etc.) to promote crop growth.
3. Industry:
   Used in metal surface treatment (such as rust removal, phosphating).
   As a chemical raw material, used in the production of detergents, flame retardants, water treatment agents, etc.
4. Laboratory:
   Common reagents for the preparation of buffer solutions and chemical analysis.
5. Medical field:
   Used in the manufacture of drugs and oral care products (such as toothpaste).

Preparation method:

1. Wet process:
   It is produced by the reaction of sulfuric acid and phosphate rock powder, the reaction is as follows:
   Ca5(PO4)3F+5H2SO4+10H2O→3H3PO4+5CaSO4⋅2H2O+HFCa5​(PO4​)3​F+5H2​SO4​+10H2​O→3H3​PO4​+5CaSO4​⋅2H2​O+HF
   This method has low cost, but the product purity is low.
2. Thermal process:
   Phosphorus pentoxide is generated by burning yellow phosphorus, and then reacted with water to produce high-purity phosphoric acid, the reaction is as follows:
   P4+5O2→2P2O5P4​+5O2​→2P2​O5​P2O5+3H2O→2H3PO4P2​O5​+3H2​O→2H3​PO4​
   This method has high product purity, but high energy consumption.

Safety precautions:

• Corrosiveness: Phosphoric acid is corrosive and can cause burns if in contact with skin or eyes. Protective equipment should be worn during operation.
• Inhalation: Phosphoric acid vapor or mist may irritate the respiratory tract. Operation should be carried out in a well-ventilated area.
• Storage: It should be stored in a cool, dry place, away from alkalis and flammable materials.

Summary:

Phosphoric acid is an important chemical raw material, which is widely used in food, agriculture, industry and medicine. When using it, you need to pay attention to its corrosiveness and safe operation specifications.