Hypophosphoric acid is one of the chemical compounds and it has acidic nature with the formula of H4P2O6, in which phosphorus is in an oxidation state. The Hypophosphoric acid consists of 4 Hydrogen, 2 Phosphorous, and 6 Oxygen atoms. and it consists of a P-P bond, for each phosphorous in the P-P bond contains 2 (P-OH) bonds and 1 (P-O) bond. The P-P bond length is 219 pm, the P-OH bond length is 159 pm and the P-O bond length is 151pm. One phosphorus atom consists of hydrogen and it is directly bonded to another Phosphorous atom. It is linked by an oxygen bridge to give phosphoric acid. Hypophosphoric acid is present as the dihydrate in the Solid state.
The Chemical formula of Hypophosphoric acid is H4P2O6. It is generally existing as dihydrate H4P2O6.2H2O, another name is di-phosphoric acid.
Structure of Hypophosphoric Acid
The Hypophosphoric acid consists of 4 Hydrogen, 2 Phosphorous, and 6 Oxygen atoms. and it consists of a P-P bond, for each phosphorous in the P-P bond contains 2 (P-OH) bonds and 1 (P-O) bond. The P-P bond length is 219 pm, the P-OH bond length is 159 pm and the P-O bond length is 151pm.

Structure of Hypophosphoric Acid
Preparation of Hypophosphoric Acid
At room temperature, red phosphorous and sodium chlorite can be combined to make Hypophosphoric acid. When white phosphorous is partially dissolved in water, it oxidizes in the air, producing a mixture of Hypophosphoric acid, phosphorous acid, and phosphoric acid.
2P + 4NaOCl2 + 2H2O ⇢ H4P2O6 + 2 NaCl
Properties of Hypophosphoric Acid
- Hypophosphoric acid is a white Solid in a dihydrate state and has no odour.
- The Melting point of Hypophosphoric acid is 54°C.
- Hypophosphoric acid is soluble in water.
- The molar mass of Hypophosphoric acid is 161.98 g/mol as a white crystalline powder.
Uses of Hypophosphoric Acid
Hypophosphoric acid has a wide range of applications. It can be used as a reducing agent as well as a bleaching agent. Aside from that, it’s a fantastic wetting agent. Not only that but it can also be used as a stimulant in pharmaceuticals as stimulant. And chemically it has wide applications like reducing agents, tetrabasic acid, and wetting agents.
Health Effects
Hypophosphoric acid is a highly corrosive substance. Chemical burns to the skin and eyes are possible. Furthermore, it may cause irritation in the upper respiratory system if inhaled. Not only that, but it has the potential to irritate the eye and eyelids. It is recommended that you remove it with water at all times. If not completed on time, it might cause long-term or irreversible vision impairment. In addition, prevent swallowing because it will harm the mucous lining of the mouth, as well as the throat, oesophagus, and stomach.
Sample Questions
Question 1: What is the chemical formula of Hypophosphoric acid and describe its structure?
Answer:
The chemical formula of Hypophosphoric acid is H4P2O6. The Hypophosphoric acid consists of 4 Hydrogen, 2 Phosphorous, and 6 Oxygen atoms. and it consists of a P-P bond, for each phosphorous in the P-P bond contains 2 (P-OH) bonds and 1 (P-O) bond. The P-P bond length is 219 pm, the P-OH bond length is 159 pm and the P-O bond length is 151 pm.

Structure of Hypophosphoric Acid
Question 2: List down some known hypophosphate salts.
Answer:
Below listed are some known hypophosphate salts:
- K4P2O6·8H2O,
- Ca2P2O6·2H2O,
- K3HP2O6·3H2O,
- K2H2P2O6·2H2O, and
- KH3P2O6 etc.
Question 3: What are some Health effects of the compound Hypophosphoric acid?
Answer:
Hypophosphoric acid is a highly corrosive substance. Chemical burns to the skin and eyes are possible. Furthermore, it may cause irritation in the upper respiratory system if inhaled. Not only that, but it has the potential to irritate the eye and eyelids. It is recommended that you remove it with water at all times. If not completed on time, it might cause long-term or irreversible vision impairment. In addition, prevent swallowing because it will harm the mucous lining of the mouth, as well as the throat, oesophagus, and stomach.
Question 4: What is the oxidation state of Phosphorus in H4P2O6?
Answer:
The oxidation state of Phosphorus in H4P2O6 is +4 only.
Question 5: Name one structural isomer of H4P2O6.
Answer:
The structural isomer of H4P2O6 is Isohypophosphoric acid.