Important Compounds of Transition Elements

Transition elements are characterized as partially filled d-orbitals in their atoms or simple ions. Transition elements are d-block elements in groupings of three to eleven. The f block elements are also known as inner transition metals, including lanthanides and actinides.

Binary compounds are formed when transition metals react with non-metals such as oxygen, nitrogen, phosphorus, halogens, sulphur, and carbon. In the industry, these chemicals are particularly significant. The following are some of the most critical transition metal compounds.

Important compounds

Transition metals are elements with partially full d orbitals . Transition elements are the d-block elements in groups 3–11. Because the d orbital is partially occupied before the f orbitals. The f-block elements, also known as inner transition metals (lanthanides and actinides), also meet this condition. The copper family (group 11) fills the d orbitals hence the next family (group 12) is technically not a transition element. Group 12 elements, on the other hand, share many of the same chemical properties as transition metals and are frequently mentioned in transition metal talks. Some scientists consider the elements of Group 12 to be transition metals.

Transition metal compounds linked to zinc, cadmium, or mercury have been known for a long time. However, it was not until the late 1960s that widely applicable synthetic procedures for establishing bonds between group 12 elements and a wide range of transition metal moieties were devised. The mononuclear transition metal moiety and the group 12 element form an electron-precise two-centre, two-electron bond in most of these compounds.

Potassium dichromate (K2Cr2O7)

Potassium dichromate is made from chromite ore (FeCr2O4). . The following are the many steps that must complete:

1. Sodium chromate preparation: Powdered ore is cooked with molten alkali in the presence of air in a reverberatory furnace to generate sodium chromate.

4FeO.Cr2O3 + 7O2+ 8Na2CO3  –> 8Na2CrO4 + 2Fe2O3 + 8CO2 

2. Sodium chromate to sodium dichromate conversion: Sodium chromate is extracted with water and acidified with sulphuric acid to produce sodium dichromate. Sodium sulphate separates as Na2SO4. 10H2O as the solution cools, leaving sodium dichromate in the solution. This solution crystallizes orange Na2Cr2O7.2H2O.

2Na2CrO4 + 2H+  →  Na2Cr2O7 + 2Na+ + H2O 

3. Sodium dichromate to potassium dichromate conversion:

(i) The least soluble sodium chloride separates and is removed by filtration. Potassium dichromate crystallizes into orange crystals when it cools. In water, potassium dichromate dissolves easily.

Na2Cr2O7 + 2KCl →  K2Cr2O7 + 2NaCl

Potassium Dichromate is an orange crystalline solid with a melting point of 671 degrees Celsius.

(ii). It dissolves readily in hot water but minimally in cold water.

(iii). Heat’s influence: When heated, K2Cr2O7 decomposes into potassium chromate and chromic oxide.

(iv) In acidic media, it functions as a potent oxidizing agent.

Sulphites are converted to sulphates, chlorides are converted to chlorine, nitrites are converted to nitrates, thiosulphates are converted to sulphates and sulphur, and stannous salts (Sn2+)  are converted to stannic salts (Sn4+).

Uses

It is used to harden gelatine film in photography.

For use as a mordant in dyeing.

The chromic acid mixture used to clean glassware comprises K2Cr2O7 and conc. H2SO4.

Potassium dichromate is used in chrome tanning in the leather industry.

As an oxidizing agent, it is used.

You are calculating the volume of ferrous salts, iodides, and sulphites.

Chrome alum, K2SO4Cr2(SO4)3.24H2O, chrome yellow (PbCrO4), and chrome red (PbCrO4)  are some of the additional chromium compounds that can be made (PbCrO4PbO).

Potassium Permanganate

Potassium permanganate is made from pyrolusite (KMnO4).  Pyrolusite is fused with KOH to generate potassium manganate, K2MnO4, in the presence of ambient oxygen or an oxidizing agent such as potassium nitrate or potassium chlorate.

6KOH + 3MnO2 + KClO3 → 3K2MnO4 + KCl + 3H2O 

Water is used to extract the green material, then oxidized to potassium permanganate electrolytically or by-passing chlorine or ozone through the solution.

6K2MnO4 + 3Cl2 → 6KMnO4 (Potassium Permanganate) + 6KCl 

Properties

(i) Potassium permanganate is a violet-coloured crystalline solid with a melting temperature of 513 degrees Celsius.

(ii) It is water-soluble and has a purple aqueous solution.

(iii) Alkaline solution effect: KMnO4 is converted to manganate and ultimately insoluble manganese dioxide in an alkaline solution.

(iv) Heat causes potassium permanganate to convert into manganate, releasing oxygen gas.

(v) When potassium permanganate is heated with alkalis, it converts into manganate, which evolves into oxygen gas.

(vi) Oxidizing Properties: KMnO4 is an effective oxidizing agent in acidic, neutral, and alkaline media.

Uses

1. It is employed as an oxidizing agent in the laboratory and industry.
2. It is used to determine how much ferrous salts, oxalates, and other reducing agents are in each volume.
3. It can detect halides, oxalates, tartrates, and sulphites, among other things.
4. It is used to disinfect water.
5. In dry cells, it is used.

Wool, cotton, silk, and other textile fibres are bleached with this chemical.

Conclusion

Transition elements are characterized as partially filled d-orbitals in their atoms or simple ions. The first transition series elements combine to generate a range of oxides with different oxidation states.

Potassium dichromate (K2Cr2O7) is made from chromite ore (FeCr2O4), and potassium permanganate is made from pyrolusite (KMnO4). These are employed as an oxidizing agent in the laboratory and the industry; potassium dichromate is used in chrome tanning in the leather industry, potassium permanganate is used in dry cells, and bleaching of wool, cotton, silk, and other materials.