Question

A hypothetical electrochemical cell is shown below
$A\left|A^{+}(x M)\right|\left|B^{+}(y M)\right| B$
The EMF measured is $+0.20\, V$. The cell reaction is

• A. $A+B^+ \rightarrow A^+ \, +B $
• B. $A^++B \rightarrow A \, +B^+ $
• C. $A^+ \, +e^- \rightarrow A,B^+\, +e^- \rightarrow B $
• D. the cell reaction cannot be predicted

Answer 1

Answer: (A)

Electrochemical cell,
$A\left|A^{+}(x M) \| B^{+}(y M)\right| B$
The EMF of cell is $+0.20 \,V$.
So, cell reaction is possible.
The half-cell reactions are given as follows
(i) At negative pole
$A \longrightarrow A^{+}+e^{-}$(oxidation)
(ii) At positive pole
$B ^{+}+ e ^{-} \longrightarrow B$(reduction)
Hence, cell reaction is
$A+B^{+} \longrightarrow A^{+}+B, \,\,\,E_{\text {cell }}^{\circ}=+0.20 \,V$