Chemistry, asked by anujsinghtomar8319, 11 months ago

Mention the preparation of potassium dichromate and potassium permanganate.Answer in detail.

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Answered by theadventureboy
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Answer:

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Explanation:

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Answered by bestanswers
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Potassium dichromate is made by combining the neutral yellow chromate of potassium in suspension, in a moderate volume of one of the potent acids. Potassium permanganate is produced by combining suspension of potassium hydroxide and powdered manganese oxide among oxidizing agents like potassium chlorate.

Preparation of Potassium Dichromate – K2Cr2O7

Potassium dichromate is an essential chemical utilized in industries as an oxidizing agent and for the development of several other compounds.

Dichromates are generally made of chromates, and this is obtained by the mixing the chromite ore along with sodium or potassium carbonate in the presence of air.

The reaction can be stated as:

4FeCr2O4 + 8Na2CO3 + 7O2 → 8Na2CrO4 + 2Fe2O3 + 8CO2

The mixture of sodium chromate (Na2CrO4) is further purified with sulphuric acid and it forms a mixture through which the crystals of orange coloured sodium dichromate (Na2Cr2O7.2H2O) can be extracted.

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

Now potassium dichromate can be extracted through a reaction from a solution of sodium dichromate with potassium chloride.

Na2Cr2O7 + 2KCl →  K2Cr2O7 + 2NaCl

Thereby, we can get the orange crystals of potassium dichromate.

Preparation of Potassium Permanganate – KMnO4

We can extract KMnO4 through the reaction of MnO2 with an alkali metal hydroxide and KNO3, an oxidizing agent.

The process will lead in the production of dark green K2MnO4 which disproportionate in an acidic or neutral medium to give permanganate.

2MnO2 + 4KOH + O2 → 2K2MnO4 + 2H2O

3MnO42- + 4H+ → 2MnO4– + MnO2 + 2H2O

Hence, making the potassium permanganate includes a reaction of MnO2 with KOH to give MnO42-, followed by electrolytic oxidation of manganate to give permanganate ion, MnO4–.

After that, the manganese ion salt gets oxidized by peroxodisulphate to permanganate ion as per the reaction is given below.

2Mn2+ + 5S2O82- + 8H2O →  2MnO4– +10SO42- + 16H+

Thus, the dark purple coloured crystals of potassium permanganate are obtained.

2KMnO4 → K2MnO4 + MnO2 + O2

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