The Iron sulphate is an inorganic salt whose chemical formula is FeSO4. It consists of a crystalline solid of a variable color, obtained industrially as a by-product of steel processing..
It is found in nature in different forms, the most common being ferrous sulfate heptahydrate, FeSO47HtwoO ("green vitriol", present in the mineral melenterite). This hydrate is easily distinguished by the bluish-green color of its crystals (lower image). Other hydrates have the general formula FeSO4XHtwoOr, where x ranges from 1 to 7.
Ferrous sulfate heptahydrate loses water molecules on heating and can be transformed into other forms of ferrous sulfate; thus, when heated to 57 ºC, it loses three water molecules and is transformed into ferrous sulfate tetrahydrate. How many in total can you lose? Seven water molecules, that is, too much water.
Ferrous sulfate is used in the treatment and prevention of iron deficiency anemia. However, it can have toxic effects, so you have to be careful in its dosage.
On the other hand, this iron salt has numerous uses and applications that include the coloring of textile material and leather; chemical reducing agent; radiation dosimeter; wood preservative agent. It is also used in the prevention of chlorosis in plants, and in engraving and lithography processes..
The FeSO4 can oxidize in air to iron (III) sulfate, Fetwo(SW4)3 at a rate that can be increased by temperature, light, or a rise in pH.
Many of the physical and chemical properties of ferrous sulfate, such as solubility in water, melting point, the type of crystals it forms, and density, depend on the number of water molecules incorporated in the crystals; that is, of its hydrates.
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The chemical formula FeSO4 highlights that this salt is composed of Fe ionstwo+ And so4two- in a 1: 1 ratio. Both ions interact through electrostatic forces in such a way that they are arranged in an orthorhombic crystal system; which, logically, corresponds to the anhydrous salt.
In the upper image, on the other hand, the structure of FeSO is shown47HtwoO. The orange sphere represents the Fe cationtwo+, which, as can be seen, coordinates with six water molecules to form an octahedron. The burden of faithtwo+ attracts the SO anion4two-, and this in turn, if observed, forms a hydrogen bond with the seventh water molecule.
The seventh water molecule (the one that is distant from the octahedron), also forms another hydrogen bond with another water molecule belonging to a neighboring octahedron. The result of these interactions is that the crystal changes from being orthorhombic to monoclinic..
As the FeSO crystals4 anhydrous hydrate, the anions SO4two- around the Faithtwo+ are replaced by H moleculestwoO. These substitutions disturb the electrons d iron, forcing them to go through different levels of energy; which are responsible for the color changes between white, bluish green.
Some SO anions4two- they can be protonated as a product of the acid medium. As a consequence, within the FeSO crystals47HtwoOr there may be molecules of HtwoSW4 if the pH is very acidic; and therefore, touching these beautiful crystals in such conditions can cause serious burns..
Ferrous sulfate or iron (II) sulfate
-Anhydrous ferrous sulfate (FeSO4)
-Ferrous sulfate heptahydrate (FeSO4.7HtwoOR)
It varies with the degree of hydration of the sulfate. For example, iron sulfate heptahydrate has a molecular weight of 278.02 g / mol; while the anhydrous one has a molecular weight of 151.91 g / mol.
It also varies with the degree of hydration. For example, the anhydrous form has white orthorhombic crystals; whereas in the heptahydrous form, the crystals are monoclinic blue-greenish.
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Anhydrous ferrous sulfate is the densest salt form (3.65 g / cm3). The heptahydrate form, on the other hand, is the least dense (1.895 g / cm3).
Likewise, this varies depending on the degree of hydration. The anhydrous form has a melting point of 680ºC (1,856ºF, 973 K) and the heptahydrate form, 60-64ºC (140-147ºF, 333-337 K).
-Monohydrate form: 44.69 g / 100 ml of water (77 ºC)
-Heptahydrate form 51.35 g / 100 ml of water (54 ºC).
Insoluble.
1.95 kPa (heptahydrate form)
1,591 (monohydrate) and 1,471 (heptahydrate).
In air it can oxidize rapidly and becomes covered with a yellow-brown color, which indicates the presence of the Fe cation.3+. The oxidation rate is increased by the addition of alkali or by exposure to light..
When heated to decomposition, it emits toxic fumes of sulfur dioxide and sulfur trioxide, leaving a reddish iron oxide as a residue..
It is a reducing agent that acts on nitric acid reducing it to nitrogen monoxide. Likewise, it reduces chlorine to chloride, and the toxic forms of chromium present in cement to chromium (III), of less toxicity.
Ferrous sulfate is produced by reacting steel (Fe) with sulfuric acid. In the method described, the following procedure is followed: the steel is used in the form of steel wool, which is previously degreased with acetone..
The steel wool is then placed in a glass beaker and fully coated with 30-40% sulfuric acid, allowing acid digestion to occur for several hours; until the steel wool disappears. More steel wool can be added and the procedure repeated several times.
Green crystals that may have formed are redissolved using water acidified to pH 1-2 with sulfuric acid. This solution is filtered on filter paper, and the pH is adjusted by adding sodium carbonate. The solution is stored, to avoid its contact with oxygen, and thus discourage the oxidation of Fetwo+ to Faith3+
Subsequently, the filtrate is subjected to evaporation at a temperature between 80-90 ºC. The procedure is carried out in Pietri capsules placed on a heating plate. Then, the green crystals formed are collected, which can be taken to a desiccator to complete their dehydration..
Ferrous sulfate is also produced by oxidation of pyrite (FeStwo).
2 FeStwo + 7 Otwo + 2 htwoO => 2 FeSO4 + 2 htwoSW4
Inhalation of FeSO4 causes irritation to the nose, throat and lungs. If you have physical contact with this salt it can cause skin and eye irritation; In addition, prolonged contact with the latter can cause a brownish stain and eye damage..
Repeated intake can cause nausea, vomiting, stomach pain, constipation, and irregular bowel movements..
Signs of ferrous sulfate poisoning include: black or bloody stools; bluish skin and nails; changes in the volume of urine excreted; fainting; dry mouth or eyes; chest pain; eat; respiratory distress.
In addition, rapid and irregular heartbeats, increased thirst and hunger, unusual paleness, and shortness of breath may occur..
Altered coagulation is an indication of ferrous sulfate poisoning, with prolongation of thrombin, prothrombin and partial thromboplastin times.
The studies carried out on the effect of ferrous sulfate on isolated muscles of the heart of rabbits, allowed to observe that it produced a reduction in the maximum tension developed by the studied cardiac muscles, as well as the maximum speed of tension development.
-It is used as a pesticide to control wheat pinch and decay of fruit trees.
-It is used in the treatment of chlorosis, a disease characterized by the yellowish color of the leaves, caused by the alkalinity of the soils..
-Ferrous sulfate controls alkalinity, lowering the pH of soils.
- Removes moss and conditions the lawn.
Within the uses of FeSO4 as reagent and in the industry there are the following:
-Analytical reagent
-Raw material for obtaining ferrite and magnetic iron oxide
-Ingredient for the manufacture of the inorganic blue pigment
-Nitric acid, chlorine and chromium reducing reagent
-In the manufacture of other sulfates
-It is used in the baths of electroplating with iron
-Wood preservative
-In aluminum etchings
-Qualitative analysis of nitrates (brown yellow test by oxidation of Fetwo+)
-Polymerization catalyst
-It is used as a precursor to the synthesis of other irons
-It is used industrially as a stain fixer
-In the manufacture of iron dye
-Mordant in wool staining
-To give maple wood a silver color
-Iron catalyst in the Fenton reaction
It is used in the treatment of iron deficiency anemia, using a dose of 150-300 mg of ferrous sulfate, three times a day, which produces a perceptible increase in the concentration of hemoglobin in a week of treatment..
Its use has also been recommended in pregnant women as a supplement to their diet. Ferrous sulfate has been used as an astringent in wound healing in cattle..
It is used in the treatment of wastewater by flocculation and also for the removal of phosphate from these waters. Ferrous sulfate heptahydrate is used in the identification of the types of fungi.
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