Six astronauts are still on the space station as part of a planned year-long stay in space, the longest tour of duty in the station's 15-year history.
The molecular formula of citric acid is C 6 H 8 O 7. The chemical formula for citric acid is best shown by a diagram of its complete structural formula. This shows how the atoms are arranged in the molecule. Citric acid has three carboxyl or-COOH groups and is triprotic in nature.
The citric acid cycle consists of 8 chemical reactions. To start, oxaloacetic acid, a four-carbon molecule, combines with acetyl coenzyme A from pyruvate oxidation. The coenzyme A molecule separates, donating the acetyl group to oxaloacetic acid so that it becomes a six-carbon molecule - this is called citric acid.