Question

Which of the following electrodes will act as anode, when connected to Standard Hydrogen Electrode?

• A. $F_2\left(g\right)/2F^{-}\left(aq\right)$
  $E^{\ominus }=+2.87V$
• B. $Cu/C{u}^{2+}{E}^{\ominus }=+0.34V$
• C. $Fe/F{e}^{2+}{E}^{\ominus }=-0.44V$
• D. $Al/A{l}^{3+}{E}^{\ominus }=-1.66V$

Answer 1

Answer: (C), (D)

$Al/A{l}^{3+}{E}^{\ominus }=-1.66V$

Anode is the positive electrode that is normally itself oxidized, i.e., it loses electrons in a chemical reaction within the cell.
All electrodes which have negative electrode potentials $(E^{\ominus }<0)$ are stronger reducing agents than $H_2$ gas and hence act as anodes when connected to standard hydrogen electrodes.

$A)Al/A{l}^3+(E^{\ominus }=-1.66V)$ has negative electrode potential, so this electrode acts as anode.

$B)Fe/F{e}^2+(E^{\ominus }=-0.44V)$ has negative electrode potential, so this electrode acts as anode.

$C\left)Cu/C{u}^{2+}\right(E^{\ominus }=+0.34V)$ has positive electrode potential, so this electrode acts as cathode.

$D\left)F_2\right(g\left)/2F^{-}\right(aq\left)\right(E^{\ominus }=+2.87V)$ has positive electrode potential, so this electrode acts as cathode.

Hence, the correct options are $\left(A\right)$ and $\left(B\right)$.