Two electron acceptors can influence this process: O and Fe ions.

It is commonly used in the laboratory as a test for the presence of Fe ions.

Similar products are also formed under acidic conditions in the presence of oxygen and Fe ions (Keller's reagent).

As a general principle, Fe ions are used to oxidize the ore.

A dirty green precipitate indicates Fe ion.

Each ferritin molecule can hold about 4000 Fe ions.

In the both cases, this is Fe ions which will be titrated subsequently.

The golden yellow color is attributed to Fe ions.

The solution detects both Fe ions and hydroxyl ions.

Formation of Fe ions and hydroxyl ions are indicated by blue and pink patches respectively.