With same d- orbital config Cr2+ is a reducing agent while Mn3+ ion is an oxidising agent. WHY? ......please explain deeply conceptually.
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Answered by
14
If something is behaving as reducing agent, that means, it itself is undergoing oxidation , that is , there is loss of electron. While for reduction there is gain of electron.
So we can explain this observation:
Cr2+ has the configuration 3d4. It can lose electron to form Cr3+ which has stable 3d3configuration ( as it has half -filled t2g level). Hence , it is reducing.
On the other hand, Mn3+ also has 3d4configuration but it can gain electron to form Mn2+ which has stable 3d5 configuration (as it is exactly half - filled). Hence oxidising.
So we can explain this observation:
Cr2+ has the configuration 3d4. It can lose electron to form Cr3+ which has stable 3d3configuration ( as it has half -filled t2g level). Hence , it is reducing.
On the other hand, Mn3+ also has 3d4configuration but it can gain electron to form Mn2+ which has stable 3d5 configuration (as it is exactly half - filled). Hence oxidising.
Answered by
3
Answer: Cr(24)= 3d5 4s1
Configuration of Cr3+ = 3d4
As Cr3+ has stable t3 2g configuration , So Cr2+ has a tendency to change to Cr3+ hence it is reducing agent.
Mn(25)= 3d5 4s2
Mn3+ = 3d4
Mn3+ changes to Mn2+ (3d5) which is half filled state configuration. HenceMn3+ act as oxidising agent.
Hope it helps
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