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Iron(II,III) oxide, or black iron oxide, is the chemical compound with formula Fe 3 O 4. It occurs in nature as the mineral magnetite . It is one of a number of iron oxides , the others being iron(II) oxide (FeO), which is rare, and iron(III) oxide (Fe 2 O 3 ) which also occurs naturally as the mineral hematite .
Iron(III) oxide is a product of the oxidation of iron. It can be prepared in the laboratory by electrolyzing a solution of sodium bicarbonate, an inert electrolyte, with an iron anode: 4 Fe + 3 O 2 + 2 H 2 O → 4 FeO(OH) The resulting hydrated iron(III) oxide, written here as FeO(OH), dehydrates around 200 °C. [18] [19] 2 FeO(OH) → Fe 2 O 3 ...
Iron oxides feature as ferrous or ferric or both. They adopt octahedral or tetrahedral coordination geometry. Only a few oxides are significant at the earth's surface, particularly wüstite, magnetite, and hematite. Oxides of Fe II. FeO: iron(II) oxide, wüstite; Mixed oxides of Fe II and Fe III. Fe 3 O 4: Iron(II,III) oxide, magnetite; Fe 4 O ...
Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite . [ 3 ] [ 4 ] One of several iron oxides , it is a black-colored powder that is sometimes confused with rust , the latter of which consists of hydrated iron(III) oxide (ferric oxide).
A metal–air electrochemical cell is an electrochemical cell that uses an anode made from pure metal and an external cathode of ambient air, typically with an aqueous or aprotic electrolyte. [1] [2] During discharging of a metal–air electrochemical cell, a reduction reaction occurs in the ambient air cathode while the metal anode is oxidized.
Simplified diagram of the iron oxide cycle. For chemical reactions, the iron oxide cycle (Fe 3 O 4 /FeO) is the original two-step thermochemical cycle proposed for use for hydrogen production. [1] It is based on the reduction and subsequent oxidation of iron ions, particularly the reduction and oxidation between Fe 3+ and Fe 2+.
Charge carrier density, also known as carrier concentration, denotes the number of charge carriers per volume. In SI units, it is measured in m −3. As with any density, in principle it can depend on position. However, usually carrier concentration is given as a single number, and represents the average carrier density over the whole material.
Charge transfer coefficient, and symmetry factor (symbols α and β, respectively) are two related parameters used in description of the kinetics of electrochemical reactions. They appear in the Butler–Volmer equation and related expressions.