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C₆H₈O₇

Citric acid

IUPAC : Citric acid
OrganicAcidBiologicalFoodEverydayIndustrialPharmaceutical

Natural tricarboxylic acid present in citrus fruits. The most widely used acidic food additive worldwide (E330) and a central intermediate of the Krebs cycle.

3D ball-and-stick representation of Citric acid (formula C₆H₈O₇). Constituent atoms: C, H, O.
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Physical properties

Molar mass192.124 g/mol
State at 20 °Csolid
Density1.665 g/cm³
Melting point426.00 K (153 °C)
Boiling point—
Solubility (H₂O)73 g/100 mL à 20 °C
pKapKa₁ = 3.13, pKa₂ = 4.76, pKa₃ = 6.40

Structure

Crystal system—
3D render modeBall-and-stick

Uses and applications

  • Food additive E330 (acidifier, antioxidant, preservative)
  • Household and industrial descaler
  • Chelating agent in cosmetics and pharmaceuticals
  • Effervescence (with NaHCO₃) in tablets and beverages
  • Metabolic intermediate (Krebs / citric acid cycle)

Safety (GHS)

GHS07 · Harmful / irritant
H statements : H319

Eye irritant at high concentration. Safe at food-grade doses.

Constituent elements

6C
Carbon
1H
Hydrogen
8O
Oxygen

References

PubChem CID311
CAS77-92-9
SMILESOC(=O)CC(O)(CC(O)=O)C(O)=O
Sources : PubChem CID 311 · NIST Chemistry WebBook