Question

Given $E_{F{e}^{2+}|Fe}^{\ominus }$ and $E_{F{e}^{3+}|F{e}^{2+}}^{\ominus }$ are -0.44 and 0.77 V respectively.
If $F{e}^{2+},F{e}^{3+}$, and $Fe$ blocks are kept together, then:

• A. $\left[F{e}^{3+}\right]$ increases and $\left[F{e}^{2+}\right]$ decreases
  
• B. $\left[F{e}^{3+}\right]$ decreases and $\left[F{e}^{2+}\right]$ increases
• C. $\left[F{e}^{3+}\right]$ inreases and $\left[F{e}^{2+}\right]$ increases
• D. $\left[F{e}^{3+}\right]$ decreases and $\left[F{e}^{2+}\right]$ decreases

Answer 1

The correct option is B $\left[F{e}^{3+}\right]$ decreases and $\left[F{e}^{2+}\right]$ increases

(Decreases, increases)
As $E_{F{e}^{3+}|F{e}^{2+}}^{\ominus }>E_F^{\ominus }{e}^{2+}|Fe$
$\therefore F{e}^{3+}$ will get reduces to $F{e}^{2+}$ and $Fe$ will get oxidized to $F{e}^{2+}$. Hence, $\left[F{e}^{3+}\right]$ decreases and $\left[F{e}^{2+}\right]$ increases.