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Questions
Account for the following:
Cr2+ is a strong reducing agent.
Give reasons for the following statement:
Cr2+ is a strong reducing agent.
Solution
Cr2+ is strongly reducing in nature. It has a d4 configuration. While acting as a reducing agent, it gets oxidised to Cr3+ (with electronic configuration d3). This d3 configuration can be written as \[\ce{t^3_{2g}}\] configuration, which is a more stable configuration.
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RELATED QUESTIONS
Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?
Which of the d-block elements may not be regarded as the transition elements?
For M2+/M and M3+/M2+ systems, the EΘ values for some metals are as follows:
| Cr2+/Cr | −0.9 V |
| Mn2+/Mn | −1.2 V |
| Fe2+/Fe | −0.4 V |
| Cr3/Cr2+ | −0.4 V |
| Mn3+/Mn2+ | +1.5 V |
| Fe3+/Fe2+ | +0.8 V |
Use this data to comment upon:
The stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+.
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(i) \[\ce{Ti^3+}\]
(ii) \[\ce{Mn2+}\]
(iii) \[\ce{Fe2+}\]
(iv) \[\ce{Co3+}\]
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Ionisation enthalpies
