Phosphorous Acid with the chemical formula H3PO3 is a chemical compound with polar molecules. This compound, also called orthophosphoric acid, is one of several oxygen-phosphorus acids used as a reducing agent in chemical decomposition.
Phosphorous Acid is a mediator in the preparation of other phosphorus compounds. It is a raw material for the preparation of phosphonates for water treatment such as control of iron and manganese, corrosion, and chlorine fixation. Alkali metal salts Phosphorous acid is widely used as an agricultural fungicide or as a superior source of plant phosphorus nutrition.
Physical and Chemical Properties:
This acid is a colorless or yellowish crystalline compound with a garlic-like taste. An unstable compound that easily absorbs moisture.
The melting point of phosphorous acid is 73.6 ° C and the boiling point is 200 ° C. At temperatures above the boiling point, the compounds tend to decompose.
The most important physical and chemical properties of this compound can be summarized in the following table:
|Density (g/cm3 at 21° C)||1.651|
|Melting Point (° C)||73.6 (164.5 °F; 346.8 K)|
|Boiling Point (° C)||200 (392 °F; 473 K) (decomposes)|
|Water Solubility (g/100 mL)||310|
|Solubility||soluble in ethanol|
|Color||white, colorless, or yellowish|
|Chemical Structure Depiction|
Formula and Structure of Phosphorous acid:
Phosphorous acid with the chemical formula H3PO3 is a polar molecular compound with a covalent bond between its constituent atoms. In this structure, phosphorus is the central atom, and two OH groups, one O atom, and one H atom are attached to it. The phosphorus atom uses sp3 hybrid orbitals to give the molecule a quadrilateral structure. Due to the electronegative difference between oxygen and phosphorus and oxygen and hydrogen, most of the bonds of this molecule are polar, which makes phosphorous acid also a polar molecule.
Difference Between Phosphorus and Phosphoric Acid:
Phosphorus and Phosphoric Acid are two types of acids that contain the chemical element phosphorus. The chemical structure of these two molecules is almost similar but their chemical and physical properties are different. The main difference between phosphorus and phosphoric acid is that phosphoric acid is diprotic while phosphoric acid is triprotic.
- Phosphorus acid can be prepared by the reaction of phosphorus trichloride with water:
PCl3 + 3H2O → H3PO4 + 3HCl
The addition of PCl3 in the presence of concentrated HCl should be very cautious and slow.
- Phosphorus acid can be produced by adding phosphorus trichloride to anhydrous oxalic acid:
PCl3 + 3(COOH）2 → H3PO3 + 3CO + 3CO2 + 3HCl
The main method of preparing Phosphorus acid is to dissolve P4O6 or tetraphosphorus hexoxide (diphosphorus trioxide) in water:
P4O6 + 6 H2O → 4 HPO(OH)2
Applications and Uses of Phosphorous acid:
- Phosphorous acid is used as a reducing agent in chemical analysis;
- Utilize to prepare phosphate salts;
- The application of phosphorous acid is that it is used in the production of basic lead phosphate as a stabilizer in PVC;
- Used as water softeners, lime cleaners, and products used in the process of collecting, purifying, and distributing water;
- Phosphorous acid is widely used as an agricultural fungicide;
- Used in solvent extraction processes to separate heavy metals-Used to prevent adhesion;
- Used as lubricants in industrial fluids such as hydraulic fluids.
Phosphorous Acid as Fertilizer:
Phosphorus is used in the form of Phosphorous acid in agriculture and as a repellent of toxins and pests.
Because Phosphorus acid and its derivatives are not metabolized in plants, it is claimed that phosphonates can help phosphorus nutrients for plant growth and should be used with extreme caution.
H3PO3 is an essential organic chemical for agricultural production that helps control the epidemic of agricultural fungi.
Phosphorus acid can be very hazardous in the case of skin contact, eye contact, and ingestion. It can also cause irritation if vapors are inhaled. This chemical can cause damage to the skin, eyes, mouth, and respiratory tract.
- Skin Contact: Immediately flush skin with water.
- Inhalation: move the person to the fresh air.
- Eye Contact: Rinse eyes with water for at least 15-20 minutes.
- Ingestion: Do not induce vomiting. Get medical aid immediately. Call a poison control center.
Packing and storage:
Store in a cool, with proper ventilation, and keep away from incompatible substances such as oxidizing agents, metals, combustible materials, and alkalis.