Citric acid molecule.
Ball-and-stick model
Picture credit: Wikimedia
A white or colorless, crystalline, sour-tasting hydroxy-carboxylic
acid that is present in citrus fruits,
such as oranges and lemons, and is an intermediate in the citric
acid cycle (Krebs cycle) in plant and animal cells. Its chemical formula
is HOOCCH2C(OH)– (COOH)CH2COOH, or C6H8O7.
Relative molecular mass 192.1, relative density 1.54, melting point 153°C.
Citric acid is made commercially by fermentation
of crude sugar with the fungus Aspergillus niger and is used for
flavoring, in effervescent salts, and as a mordant
(color-fixer) in dyeing.