Which is a stronger reducing agent Cr2+ or Fe2+ and why?
The following reactions are involved when Cr2+ and Fe2+ act as reducing agents.
`Cr^(2+) -> Cr^(3+)Fe^(2+) -> Fe^(3+)`
The `E_((Cr^(3+))/(Cr^(2+)))^@` value is -0.14 V and `E_(" "(Fe^(3+))/(Fe^(2+)))^@` is + 0.77 V. This means that Cr2+ can be easily oxidized to Cr3+, but Fe2+ does not get oxidized to Fe3+ easily. Therefore, Cr2+ is a better reducing agent that Fe3+.
Cr2+ is a stronger reducing agent than Fe2+. This is because E°(Cr3+/Cr2+) is negative (- 0.41V) whereas E°(Fe3+/Fe2+) is positive (+ 0.77 V). Thus, Cr2+ is easily oxidised to Fe3+ but Fe2+ cannot be easily oxidised to Fe3+.
In what way is the electronic configuration of the transition elements different from that of the non-transition elements?
How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
What are the characteristics of the transition elements and why are they called transition elements?
Write down the number of 3d electrons in each of the following ions:
Ti2+, V2+, Cr3+, Mn2+, Fe2+, Fe3+, CO2+, Ni2+ and Cu2+.
Indicate how would you expect the five 3d orbitals to be occupied for these hydrated ions (octahedral).