|IUPAC name||2-hydroxypropane-1,2,3-tricarboxylic acid|
|Other names||3-carboxy-3-hydroxypentanedioic acid|
|Molar mass||192.124 g/mol (anhydrous)
210.14 g/mol (monohydrate)
|Appearance||crystalline white solid|
|Density||1.665 g/cm3(1.5g/cm3 for monohydrate)|
153 °C, 426 K, 307 °F
175 °C, 448 K, 347 °F (decomposes)
|Solubility in water||73 g/100 ml (20 °C)|
|Acidity (pKa)||pKa1 = 3.09
pKa2 = 4.75
pKa3 = 5.41 
|Main hazards||skin and eye irritant|
|Related compounds||sodium citrate, calcium citrate|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)|
Citric acid is a weak organic acid. It can be found in citrus fruits ( like oranges). It is used by organisms for Krebs cycle. It acts like a preservative when added to food. It is also used to add a sour (acidic) taste to foods and soft drinks. In the European Union it is known as E 330, as a food additive.
Carl Wilhelm Scheele was the first who could extract citric acid from lemons, in 1782. The substance was probably known to alchemists, perhaps with a different name. The Arabian alchemist Geber is said to have discovered citric acid in the 9th century. Citric Acid contains 6 Carbon atoms, 8 Hydrogen atoms and 7 Oxygen atoms. Its chemical formula is C6H8O7.
Main uses[change | change source]
- As a water softener
- It is often used in detergents, to avoid the smell of acid, esp. Acetic acid
- As a preserving agent
- Citric acid and its salts prevent blood clotting. Blood donations are kept liquid using citric acid.
References[change | change source]
- Dawson, R. M. C.; et al. (1959). Data for Biochemical Research. Oxford: Clarendon Press.