question_answer 31)

How would you account for the following (a) Of the d4 species, Cr2+ is strongly reducing while Mn3+ is strongly oxidising in nature. (b) Cobalt (II) is stable in aqueous solution but in the presence of complexing reagents, it is easily oxidised. (c) The d1 configuration is very unstable in ions.

Answer:

(a) E° value of Cr3+ /Cr2+ is negative while that ofMn3+/Mn2+ is positive. This means Cr2+ ions can lose electrons to form Cr3+ ions and act as a reducing agent while Mn3+ ions can accept electrons and can act as oxidising agent. (b) Cobalt (II) is stable in aqueous solution but in the presence of complexion agent, it undergoes change in oxidation state from +2 to +3 and is easily oxidised. This is because CO3+ has more tendency to form coordination complexes than Co2+. (c) The ions with d1 configuration can easily lose one more electron to acquire extra stability of d0 configuration.