Transition and Inner Transition Elements — Chemistry STD 12 — Question
Tamilnadu BoardEnglish MediumSTD 12ChemistryTransition and Inner Transition Elements3 Marks
Question
Which is the stronger reducing agent $Cr ^{2+}$ or $Fe ^{2+} ?$
✓
Answer
$Cr^{2+} \text { and } Fe^{2+}$
$Cr(Z=24)$
Electronic configuration - [Ar] $3 d^5 4 s^1$
$Cr^{2+} \text { Electronic configuration - }[Ar] 3 d^4 4 s^0$
$Fe(Z=26)$
Electronic configuration - [Ar] $3 d^6 4 s^2$
$Fe^{2+} \text { Electronic confimiration }-[Ar] 3 d^6 4 s^0$
If the standard electrode potential $\left(E^0\right)$ of metal is large and negative, the metal is a powerful reducing agent
$Cr^{2+}+2 e^{-} \longrightarrow C r$
$Fe^{2+}+2 e^{-} \longrightarrow F e$
$E^0=-0.91 V$
$E^0=-0.44 V$
By comparing the above equation, $Cr ^{2+}$ is a powerful reducing agent.
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