Courses
Courses for Kids
Free study material
Offline Centres
More
Store Icon
Store
seo-qna
SearchIcon
banner

The crystal field stabilization energy (CFSE) [Fe(H2O)6]Cl2 and K2[NiCl4], respectively, are:
a.) -0.4 Δ 0 and -0.8 Δ t
b.) -0.4 Δ 0 and -1.2 Δ t
c.) -2.4 Δ 0 and -1.2 Δ t
d.) -0.6 Δ 0 and -0.8 Δ t

Answer
VerifiedVerified
500.7k+ views
1 likes
like imagedislike image
Hint: Crystal field theory states that there is a difference of 10Dq between eg and t2g energy levels. When an electron goes into t2g which is a lower energy level, it stabilizes the system by an amount of -4Dq and when an electron goes into eg level, it destabilizes the system by +6Dq.

Complete answer:
The stability which results due to placing of a transition metal ion into a field that is caused by the set of ligands which surround it, is called Crystal field stabilization energy. In the complex,  [ Fe(H2O)6]Cl2, Fe forms a +2 ion i.e.  [ Fe(H2O)6]+2.
The electronic configuration of Iron in +2 becomes  [ Ar ] 3d3.
is a weak field ligand and hence pairing of electrons does not occur. Electrons in t2g are given as t2g2, 1, 1.

Formula for calculating crystal field stabilization energy is Δ = no. of e in t2g × (-0.4) + no. of e in eg × (0.6)

Thus, for this complex - Δ = 4Δ0× (-0.4) + 2Δ0 × (0.6)
                                              Δ = - 0.4Δ0
In the complex, K2 [ NiCl4] charge on Nickel is +2 as it forms  [ NiCl4]2.

    The electronic configuration of Nickel in +2 is  [ Ar ] 3d8.

 is also a weak field ligand and hence pairing does not occur and the complex formed has tetrahedral geometry. Electrons in eg are eg2, 2.
Putting these values in the formula we get,  Δ = -0.6 × 4 Δ t + 0.4 × 4 Δ t
                                                                                   = -2.4 Δ t + 1.6 Δ t
                                                                              Δ = -0.8 Δ t

So, the correct answer is “Option A”.

Note: Complexes which have a higher number of unpaired electrons are called as high spin complexes and the ones which have low number of unpaired electrons are called as low spin complexes. Most of the time, high spin complexes have weak field ligands and hence their splitting energy has lower value. Conversely, low spin complexes have strong field ligands and hence have higher value of splitting energy.
Latest Vedantu courses for you
Grade 10 | CBSE | SCHOOL | English
Vedantu 10 CBSE Pro Course - (2025-26)
calendar iconAcademic year 2025-26
language iconENGLISH
book iconUnlimited access till final school exam
tick
School Full course for CBSE students
PhysicsPhysics
Social scienceSocial science
ChemistryChemistry
MathsMaths
BiologyBiology
EnglishEnglish
₹38,500 (9% Off)
₹35,000 per year
Select and buy