FAS Solution Full Form

What is the full form of FAS?

The full form of the FAS Solution is the Ferrous Ammonium Sulphate. Mohr's salt, also known as ammonium iron(II) sulphate, is an inorganic chemical having the formula (NH4)2Fe(SO4)2(H2O)6. It is categorised as a double salt of ferrous sulphate and ammonium sulphate because it contains two distinct cations, Fe2+ and NH4+. It is a typical laboratory reagent because it crystallises easily and does not oxidise in the presence of air. The aqua complex [Fe(H2O)6]2+, with octahedral molecular geometry, is produced when ferrous ammonium sulphate dissolves in water, just like the other ferrous sulphate salts. Mohrite is the mineral form of it.

Structure

This substance belongs to a class of double sulphates known as Schönites or Tutton's salts. The crystal structure of Tutton's salts is monoclinic, and their formula is M2N(SO4)2.6H2O (M = different monocations). Octahedral [Fe(H2O)6]2+ centres that are hydrogen bonded to sulphate and ammonium make up crystals in terms of bonding. Karl Friedrich Mohr, a German chemist who made significant contributions to titration methods in the 19th century, is the name-bearer of Mohr's salt.

Applications

This salt is the favoured source of ferrous ions in analytical chemistry because it has a long shelf life and is oxidation-resistant. This stability partially extends to solutions that depict how pH affects the ferrous/ferric redox pair. At high pH levels, this oxidation happens more quickly. Mohr's salt solutions become slightly acidic due to the ammonium ions, which slows down the oxidation process. To prevent ferric iron from oxidising, sulfuric acid is frequently added to solutions. It is employed in Fricke's dosimeter to gauge high gamma radiation dosages.

Preparation

In order to make Mohr's salt, hydrated ferrous sulphate and ammonium sulphate are first dissolved in water with a small amount of sulfuric acid, and the resulting solution is then allowed to crystallize. Light-green crystals of ferrous ammonium sulphate are produced. When heated, this salt ionises to release all of its cations and anions.

Contaminants

Magnesium, nickel, manganese, lead, and zinc are typical contaminants that frequently form isomorphous salts.

Preparation of FAS

Aim

• Making ferrous ammonium sulphate from ferrous sulphate and ammonium sulphate in the presence of acid produces Mohr's salt.

Theory

• FeSO4.(NH4)2SO4.6H2O is the formula for ferrous ammonium sulphate. In water with a small amount of sulfuric acid, an equimolar mixture of hydrated ferrous sulphate and ammonium sulphate is dissolved to create the compound. Ferrous ammonium sulphate separates from the solution as a result of the crystallisation of the solution.

• The chemistry is described below.

• FeSO4.(NH4)2SO4 + 6H2O → FeSO4.(NH4)2SO.6H2O (Mohr’s salt)

• In this experiment, sulfuric acid is added to stop this salt from hydrolyzing. In contrast to ferrous sulphate, ferrous ammonium sulphate is a pale green crystalline substance. It is a superior volumetric reagent to ferrous sulphate because it is less easily oxidised than FeSO4.

• Mohr's salt, which contains two simple salts, is also known as double salt. In aqueous solutions, it completely dissociates. Mohr's salt separates into the ions Fe2+, NH4+, and SO42-, each of which undergoes a unique chemical analysis.

• Light green transparent octahedral crystals make up Mohr's salt. It dissolves in water to produce an acidic solution that colours blue litmus paper red and causes effervescence when combined with sodium bicarbonate, which releases carbon dioxide.

• Mohr's salt, also known as ferrous ammonium sulphate, is made by dissolving an equimolar mixture of hydrated ferrous sulphate and ammonium sulphate in water that contains a small amount of sulfuric acid. Crystallization is applied to the solution.

Materials Required

• Conical flask

• Tripod stand

• Burner

• Funnel

• Watch glass

• Glass rod

• Filter paper

• Wire gauze

• China dish

• Ferrous sulfate

• Ammonium sulfate

• Dilute sulphuric acid

Procedure

• Separately weigh 3.5 g of ammonium sulphate and 7 g of ferrous sulphate.

• In a beaker of diluted sulfuric acid, combine ferrous and ammonium sulphate in water.

• To obtain a clear solution, gently warm the solution.

• By heating the solution in a china dish over a sand bath until the crystallisation point is reached, filter the solution to remove any suspended contaminants and concentrate the clear filtrate.

• While heating, the solution will occasionally be stirred.

• For gradual cooling, don't disturb the solution. The ferrous ammonium sulphate crystal will eventually separate from the solution.

• Decant the crystals from the mother liquor and wash them in cold water to separate them.

• Dry the crystals by spreading them on a porous plate or in between the filter paper folds.

Observations

Results

The yield of ferrous ammonium sulfate is _______ gm.