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Ammonium ferric citrate

physical science Maturity 11-13 Next article →

Ammonium ferric citrate is a unique chemical compound. It is also known as ferric ammonium citrate. It can also be called ammoniacal ferrous citrate. This substance is classified as a double salt. It contains iron that is in a trivalent state. This means the iron has a specific charge. This compound is quite important in many different fields. It is used in food, medicine, and science labs.

The chemical structure of this compound is very specific. Its formula is C6H9Fe Citrate. It is built from citric acid and ammonium. In this structure, the citric acid undergoes a process called deprotonation. This means the citric acid loses four protons. Specifically, all three carboxyl groups and the central hydroxyl group are deprotonated. This chemical arrangement is very important for its behavior.

How the molecules connect determines how the substance acts. In its crystal structure, the parts link together in a precise way. The deprotonated hydroxyl group attaches to the ferric center. Two of the carboxylate groups also ligate to the ferric center. The third carboxylate group coordinates with the ammonium. This specific bonding pattern is a distinguishing feature. It makes the compound very soluble in water. This is different from regular ferric citrate, which does not dissolve easily.

This high solubility allows for many practical uses. One major area is the food industry. Ammonium ferric citrate is used as a food ingredient. It has the international number INS 381. In food, it functions as an acidity regulator. This helps manage the acid levels in what we eat. A very famous example is the Scottish beverage Irn-Bru. This drink uses the compound as part of its recipe.

In scientific laboratories, the compound performs specialized tasks. It can act as a reducing agent. This means it helps change the state of certain metal salts. It is used for metals with low activity, such as gold and silver. It is also used in the cyanotype photographic process. In this process, it works alongside potassium ferricyanide. This combination helps create photographic images.

Medical science also relies on this compound for important work. It is used as a contrast medium in medical imaging. This helps doctors see better during scans. It is also used as a hematinic. A hematinic is a substance that helps the body with blood. Furthermore, it is used in a specific laboratory test. This is called the Kligler's Iron Agar test, or the KIA test.

The KIA test is a tool for identifying bacteria. Specifically, it identifies bacteria in the enterobacteriaceae group. The test works by observing how these bacteria use different sugars. Scientists look to see if the metabolism of the sugars produces hydrogen sulfide. This chemical reaction helps identify the exact type of bacteria present. This makes ammonium ferric citrate a vital tool for microbiology.

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