LIVE Course for free

Rated by 1 million+ students
Get app now
0 votes
17 views
in Chemistry by (30.0k points)
closed by

Three complexes,

[CoCl(NH3)5]2+ (I)

[Co(NH3)5H2O]3+ (II) and

[Co(NH3)6]3+ (III)

absorb light in the visible region. The correct order of the wavelength of light absorbed by them is:
1. (III) > (I) > (II)
2. (III) > (II) > (I)
3. (II) > (I) > (III)
4. (I) > (II) > (III)

1 Answer

0 votes
by (25.6k points)
selected by
 
Best answer
Correct Answer - Option 4 : (I) > (II) > (III)

Concept:

Wavelength of the energy absorbed by the coordination compound is inversely proportional to crystal field stabilization energy (CFSE).

CFSE depends on four main properties:

(i) Geometry like octahedral or tetrahedral.

(ii) Charge of the compound in case of metals.

(iii) Nature of ligand as like strong or weak.

(iv) Size of the orbital like 3d, 4d, or 5d etc.

From the question, the three compounds are of Cobalt thus all three possess same octahedral structure and geometry does not work here.

Now all the three cobalt must have charge of 3+ and we cannot classify according to charge.

Similarly size also does not play any differentiating role in here. So only nature of the ligand varies.

Wavelength of the energy absorbed by the coordination compound is inversely proportional to ligand field strength of the given coordination compound. The strong field ligand can cause higher splitting of the d-orbitals. The decreasing order of the ligand field strength is NH3 > H2O > Cl.

Therefore, decreasing order of the absorbed wavelength is

(I) > (II) > (III)

So, option (d) is the correct answer. 

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...