Citric acid is a weak organic acid. It can be found in citrus fruits (like oranges). It acts like a preservative. 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 six carbon atoms, eight hydrogen atoms and seven oxygen atoms, making the chemical formula C6H8O7.
- As a water softener.
- It is often used in detergents, to avoid the smell of acid.
- As a perserving agent.
- Citric acids and its salts prevent blood clotting. Blood donations are kept liquid using citric acid.