Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12
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What Can Be Inferred from the Magnetic Moment Values of the Following Complex Species? - Chemistry

What can be inferred from the magnetic moment values of the following complex species?

Example Magnetic Moment (BM)

K4[Mn(CN)6] 2.2

[Fe(H2O)6]2+ 5.3

K2[MnCl4] 5.9

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Solution

Magnetic moment (`mu`) is given as `mu = sqrt(n(n+2))`

For value n = 1, `mu = sqrt(1(1+2)) = sqrt3 = 1.7321`

For value n = 2, `mu = sqrt(2(2+2)) = sqrt8 = 2.83`

For value n = 3, `mu = sqrt(3(3+2)) = sqrt15 = 3.87`

For value n = 4, `mu = sqrt(4(4+2)) = sqrt24 = 4.899`

For value n = 5, `mu = sqrt(5(5+2)) = sqrt35 = 5.92`

1) K4[Mn(CN)6]

For in transition metals, the magnetic moment is calculated from the spin-only formula. Therefore,

`sqrt(n(n+2)) = 2.2`

We can see from the above calculation that the given value is closest to n = 1. Also, in this complex, Mn is in the +2 oxidation state. This means that Mn has 5 electrons in the d-orbital.

Hence, we can say that CN− is a strong field ligand that causes the pairing of electrons.

(ii) [Fe(H2O)6]2+

`sqrt(n(n+2)) = 5.3`

We can see from the above calculation that the given value is closest to n = 4. Also, in this complex, Fe is in the +2 oxidation state. This means that Fe has 6 electrons in the d-orbital.

Hence, we can say that H2O is a weak field ligand and does not cause the pairing of electrons.

(iii) K2[MnCl4]

`sqrt(n(n+2)) = 5.9`

We can see from the above calculation that the given value is closest to n = 5. Also, in this complex, Mn is in the +2 oxidation state. This means that Mn has 5 electrons in the d-orbital

Hence, we can say that Cl− is a weak field ligand and does not cause the pairing of electrons.

  Is there an error in this question or solution?
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APPEARS IN

NCERT Class 12 Chemistry Textbook
Chapter 8 The d-block and f-block Elements
Q 38 | Page 236
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