Ferrate
Encyclopedia
In chemistry
, ferrate(VI) refers either to the anion , in which iron
is in the +6 oxidation state
, or to a salt containing this anion. The term ferrate is often used to mean ferrate(VI), although according to IUPAC naming conventions, it may also refer to other iron-containing oxyanion
s, such as ferrate(V) and ferrate(IV).
iron in aqueous medium with strong oxidizing agents under alkaline conditions
, or in the solid state by heating a mixture of iron filings and powdered potassium nitrate.
Ferrates can also be produced by heating iron(III) hydroxide with sodium hypochlorite in alkaline solution
:
The yield may be increased by precipitating the resulting ion with
, forming barium ferrate
.
The ferrate(VI) ion has two unpaired electron
s, and is thus paramagnetic
. It has tetrahedral molecular geometry
.
values, decomposing to iron(III):
The reduction goes through intermediate species in which iron has oxidation states +5 and +4. These have been found to be even more reactive than ferrate(VI). In alkaline conditions, ferrates are more stable, lasting for about 8 to 9 hours at pH 8 or 9.
Aqueous solutions of ferrates are pink when dilute, and deep red or purple at higher concentrations. The ferrate ion is a stronger oxidizing agent
than permanganate
, and will oxidize
to
, and ammonia
to elemental nitrogen
.
Ferrates are excellent disinfectants, and are capable of removing heavy metals, phosphate
s, and destroying virus
es.
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, ferrate(VI) refers either to the anion , in which iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
is in the +6 oxidation state
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...
, or to a salt containing this anion. The term ferrate is often used to mean ferrate(VI), although according to IUPAC naming conventions, it may also refer to other iron-containing oxyanion
Oxyanion
An oxyanion or oxoanion is a chemical compound with the generic formula AxOyz− . Oxoanions are formed by a large majority of the chemical elements. The formulae of simple oxoanions are determined by the octet rule...
s, such as ferrate(V) and ferrate(IV).
Synthesis
Ferrate(VI) salts are formed by oxidizingRedox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
iron in aqueous medium with strong oxidizing agents under alkaline conditions
Base (chemistry)
For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...
, or in the solid state by heating a mixture of iron filings and powdered potassium nitrate.
Ferrates can also be produced by heating iron(III) hydroxide with sodium hypochlorite in alkaline solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
:
- 2 + 3 + 4 → 2 + 5 + 3
The yield may be increased by precipitating the resulting ion with
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
, forming barium ferrate
Barium ferrate
Barium ferrate is the chemical compound of formula BaFeO4. This compound contains iron in the +6 oxidation state. It is isostructural with BaSO4, and contains the tetrahedral [FeO4]2− anion.-Preparation and chemistry:...
.
The ferrate(VI) ion has two unpaired electron
Unpaired electron
In chemistry, an unpaired electron is an electron that occupies an orbital of an atom singly, rather than as part of an electron pair. As the formation of electron pairs is often energetically favourable, either in the form of a chemical bond or as a lone pair, unpaired electrons are relatively...
s, and is thus paramagnetic
Paramagnetism
Paramagnetism is a form of magnetism whereby the paramagnetic material is only attracted when in the presence of an externally applied magnetic field. In contrast with this, diamagnetic materials are repulsive when placed in a magnetic field...
. It has tetrahedral molecular geometry
Tetrahedral molecular geometry
In a tetrahedral molecular geometry a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1 ≈ 109.5° when all four substituents are the same, as in CH4. This molecular geometry is common throughout the first...
.
Properties
The ferrate(VI) anion is unstable at neutral or acidic pHPH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
values, decomposing to iron(III):
- + 3 + 8 + 4
The reduction goes through intermediate species in which iron has oxidation states +5 and +4. These have been found to be even more reactive than ferrate(VI). In alkaline conditions, ferrates are more stable, lasting for about 8 to 9 hours at pH 8 or 9.
Aqueous solutions of ferrates are pink when dilute, and deep red or purple at higher concentrations. The ferrate ion is a stronger oxidizing agent
Oxidizing agent
An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...
than permanganate
Permanganate
A permanganate is the general name for a chemical compound containing the manganate ion, . Because manganese is in the +7 oxidation state, the permanganate ion is a strong oxidizing agent. The ion has tetrahedral geometry...
, and will oxidize
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
to
Chromate
Chromate salts contain the chromate anion, CrO42−. Dichromate salts contain the dichromate anion, Cr2O72−. They are oxyanions of chromium in the oxidation state +6. They are moderately strong oxidizing agents.- Chemical properties :...
, and ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
to elemental nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
.
Ferrates are excellent disinfectants, and are capable of removing heavy metals, phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
s, and destroying virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es.