Chemical Science Revision Notes on Spinels - Download PDF!

By Astha Singh|Updated : January 28th, 2022

Are you looking for some short and reliable notes during your CSIR-NET preparations? Then, you have come to a perfect place!

Candidates who are preparing for their CSIR NET exam might need to get some short study notes and strategies to apply while preparing for the key exam of their life. At this point in time, We at BYJU'S Exam Prep come up with short notes on Spinels which comes under the Inorganic Chemistry section of the Chemical Science syllabus

This set of short notes on Spinels has been meticulously designed by our experienced subject-matter experts to give you the most standard set of study materials to be focused upon. In this cut-throat competitive world, students need to prepare themselves with the best study materials to help them in the learning process and for their future. Here we are offering the best study notes that are reliable and can be used by the students during their preparations for the upcoming CSIR-NET 2022 exam.

Study Notes on Spinels

Structure of spinels:

Spinels have the general chemical formula AB2X4. Here,

AII- a divalent cation like Mn, Cr, Fe, Co, Ni

BIII- a trivalent cation like Ga, Al, Cr, Mn, Fe

Mixed metal oxides having the composition AIIB2III O4 are called spinels. A and B may be different metals or the same metal in different oxidation states. Spinels are classified into two types: normal spinels, AII[B2III]O4 inverse spinels, BIII[AII BIII]O4. In normal spinels, A occupies tetrahedral interstices, while B occupies octahedral interstices. The compound NiAl2O4 is an example of normal spinel. In inverse spinels, half B's occupy tetrahedral sites and half B's octahedral sites, while A is in octahedral interstices. An example of an inverse spinel is Fe3O4, when it may be represented as, FeIII[FeIIFeIII]O4.

For transition metal oxide spinels, the choice of the normal and inverse spinels is generally driven by the CFSE of ions in the tetrahedral and octahedral sites. For spinels containing 3d elements like Mn, Fe, Cr and Co, the electronic configuration is typically high spin because O2- is a weak field ligand.

Whether a particular spinel will acquire normal structure or inverse structure largely depends on CFSE. That structure prevails which has a greater negative value of CFSE. For example, consider the mixed manganese oxide, Mn3O4. If it is a normal spinel, its CFSE may be calculated as follows:

MnII [Mn2III] O4

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Total CFSE byjusexamprep

If it is an inverse spinel, the crystal field stabilization energy may be calculated as follows:

MkIII [MnIIMnIII] O4

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The normal spinel has a greater negative CFSE and hence this structure prevails.

(II) (III)

Co3O4  byjusexamprepCoCo2O4

Co3+ is a low spin in the field produced by oxide ions.

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Short Notes on Spinels - Download PDF Now

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