d and f Block ElementshardMCQ SINGLE⭐ Must-Do

Both () and () act as reducing agents, tending to oxidize to the state. However, in an aqueous solutd and f Block Elements Chemistry Question

Question

Both $Cr^{2+}$ ($3d^4$) and $Fe^{2+}$ ($3d^6$) act as reducing agents, tending to oxidize to the $+3$ state. However, in an aqueous solution, $Cr^{2+}$ is an exponentially stronger reducing agent than $Fe^{2+}$. Why?

Answer: A

💡 Solution & Explanation

$Cr^{2+} \rightarrow Cr^{3+}$ ($t_{2g}^3$ in water) provides massive crystal field stabilization energy. $Fe^{2+} \rightarrow Fe^{3+}$ ($d^5$ in water) is stable due to exchange energy, but the $t_{2g}^3$ state in aqueous media provides a comparatively larger overall thermodynamic drive.

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