Chemical properties of iron
Iron Fe, atomic number 26, relative atomic mass […]
Iron Fe, atomic number 26, relative atomic mass 55.847. Iron has a variety of allotropes, such as alpha iron, beta iron, gamma iron, б iron and the like. Iron is a relatively active metal that is placed in front of hydrogen in the metal activity sequence. At normal temperature, iron does not easily react with non-metallic elements such as oxygen, sulfur, and chlorine in dry air, and reacts violently at high temperatures. Iron is burned in oxygen to form Fe3O4, and red hot iron and water vapor react to form Fe3O4. Iron is easily soluble in dilute mineral acid and concentrated hydrochloric acid to form a divalent iron salt and release hydrogen.
When concentrated sulfuric acid or concentrated nitric acid is encountered at normal temperature, an oxide protective film is formed on the surface to "passivate" the iron, so that the concentrated iron or concentrated nitric acid can be contained in the iron product. Iron is a variable price element, and the common valence states are +2 and +3.
When iron reacts with sulfur, copper sulfate solution, hydrochloric acid, dilute sulfuric acid, etc., it loses two electrons and becomes +2. It reacts with Cl2, Br2, nitric acid and hot concentrated sulfuric acid to be oxidized to Fe3+. Fe3O4 formed by the reaction of iron with oxygen or water vapor can be regarded as FeO·Fe2O3, of which 1/3 of Fe is +2 valence, and 2/3 is +3 valence. The +3 valence compound of iron is relatively stable.