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H₃PO₄
Phosphoric acid
IUPAC : Phosphoric acid
AcidIndustrialFoodLaboratory
Weak triprotic acid, ubiquitous in the phosphate-fertiliser industry and used as an acidifying additive (E338) in carbonated drinks.
3D ball-and-stick representation of Phosphoric acid (formula H₃PO₄). Constituent atoms: H, P, O.
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Physical properties
Molar mass97.994 g/mol
State at 20 °Csolid
Density1.685 g/cm³
Melting point315.50 K (42.35 °C)
Boiling point—
Solubility (H₂O)miscible (en solution aqueuse)
pKapKa₁ = 2.15, pKa₂ = 7.20, pKa₃ = 12.35
Structure
Crystal system—
3D render modeBall-and-stick
Uses and applications
- Phosphate fertiliser production (superphosphate, DAP, MAP)
- Food additive E338 (acidifier in colas and sodas)
- Metal surface treatment (anti-rust phosphating)
- Dentistry (enamel etching)
- Phosphate buffer in biochemistry (PBS)
Safety (GHS)
GHS05 · Corrosive
H statements : H314
Corrosive at high concentration. Dilute (food-grade) solutions are safe.
Constituent elements
References
Sources : PubChem CID 1004 · NIST Chemistry WebBook