H

Hypophosphorous acid

IUPAC: phosphinic acid

H3O2P Acids CAS 6303-21-5
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Quick Reference
Formula / NotationH3O2P
CAS Number6303-21-5
Molecular Weight65.996
Melting Point26.5 °C
Boiling PointDecomposes upon heating >133 °C
DensityMarketed in aqueous solutions of varying concentrations, 50% (density 1.274), 30-32% (density 1.13),
SolubilityMiscible with water
AppearanceHypophosphorous acid appears as colorless oily liquid or deliquescent crystals with a sour odor. Density 1.439 g / cm3. Melting point 26.5 °C. Inhalation of vapors irritates or burns the respirato...
Also Known Asphosphinic acid; Acid, Phosphinic; RefChem:929168; DTXCID401012094; 228-601-5; 6303-21-5; 8B1RL9B4ZJ; CHEBI:29031; DTXSID90873902; Hydroxyphosphine oxide
CategoryAcids

What is Hypophosphorous acid?

Hypophosphorous acid (H3O2P) is an acid that appears as Hypophosphorous acid appears as colorless oily liquid or deliquescent crystals with a sour odor. Density 1.439 g / cm3. Melting point 26.5 °C. Inhalation of vapors irritates or burns the respirato.... It has a molecular weight of 65.996 g/mol. Its IUPAC name is phosphinic acid. Boiling point: Decomposes upon heating >133 °C. Melting point: 26.5 °C.

Formula & Notation

H3O2P

IUPAC Name: phosphinic acid

Other Names / Synonyms: phosphinic acid; Acid, Phosphinic; RefChem:929168; DTXCID401012094; 228-601-5; 6303-21-5; 8B1RL9B4ZJ; CHEBI:29031; DTXSID90873902; Hydroxyphosphine oxide

Properties & Characteristics

Appearance: Hypophosphorous acid appears as colorless oily liquid or deliquescent crystals with a sour odor. Density 1.439 g / cm3. Melting point 26.5 °C. Inhalation of vapors irritates or burns the respirato.... Molecular formula: H3O2P. Molecular weight: 65.996 g/mol. Boiling point: Decomposes upon heating >133 °C. Melting point: 26.5 °C. Density: Marketed in aqueous solutions of varying concentrations, 50% (density 1.274), 30-32% (density 1.13), 10% (density 1.04). Solubility: Miscible with water. Vapor pressure: 0.00323 mmg Hg at 25 °C (effusion method: vapor pressure balance). LogP: -1.1.

Physical Data

PropertyValue
Melting Point26.5 °C
Boiling PointDecomposes upon heating >133 °C
DensityMarketed in aqueous solutions of varying concentrations, 50% (density 1.274), 30-32% (density 1.13),
Molecular Weight65.996
SolubilityMiscible with water
AppearanceHypophosphorous acid appears as colorless oily liquid or deliquescent crystals with a sour odor. Density 1.439 g / cm3. Melting point 26.5 °C. Inhalation of vapors irritates or burns the respirato...

Uses & Applications

Used in industrial chemical synthesis, fertilizer production, battery electrolytes, metal processing, and laboratory acid-base reactions.

Safety Information

Corrosive. Causes severe burns to skin, eyes, and respiratory tract. Wear appropriate PPE including gloves, goggles, and lab coat. Consult SDS before use.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Hypophosphorous acid
Formula H3O2P
CAS Number 6303-21-5
Molecular Weight 65.996
Category Acids
Synonyms phosphinic acid; Acid, Phosphinic; RefChem:929168; DTXCID401012094; 228-601-5; 6303-21-5; 8B1RL9B4ZJ; CHEBI:29031; DTXSID90873902; Hydroxyphosphine oxide

Frequently Asked Questions

Hypophosphorous acid (H3O2P) is an acid that appears as Hypophosphorous acid appears as colorless oily liquid or deliquescent crystals with a sour odor. Density 1.439 g / cm3. Melting point 26.5 °C. Inhalation of vapors irritates or burns the respirato.... It has a molecular weight of 65.996 g/mol. Its IUPAC name is phosphinic acid. Boiling point: Decomposes upon heating >133 °C. Melting point: 26.5 °C.

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Editorial standards: Chemical data is sourced from peer-reviewed literature, CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA, and IAEA. For educational purposes only — always consult official SDS documentation and qualified professionals before handling chemicals.