Citric acid (CA), also known as citric acid, with the molecular formula C ₆ H ₈ O ₇, is an important organic weak acid. It is a colorless crystal, odorless, easily soluble in water, and has an acidic solution. In biochemistry, it is an intermediate in the citric acid cycle (tricarboxylic acid cycle), which occurs in the metabolism of all aerobic organisms. Citric acid is widely used as an acidity regulator (GB2760-2014), flavoring agent, and chelating agent.

Basic characteristics:

Melting point: 153-159 oC

Boiling point: 309.6 ± 42.0 oC (760 mmHg)

Vapor density: 7.26 (vs air)

Vapor pressure:<0.1 hPa (20 oC)

Refractive index: 1.493~1.509

Flash point: 155.2 ± 24.4 oC

Solubility: soluble in water, ethanol, ether, insoluble in benzene, slightly soluble in chloroform

PH value: 3.24 (1 mM aqueous solution); 2.62 (10 mM aqueous solution); 2.08 (100 mM aqueous solution)