Question

Given two reactions and their electrode potential values:
Reaction 1 :
$A(aq.)\rightleftharpoons A^{n+}(aq.)+n{e}^{-}$
$E^{\circ }=+2V$

Reaction 2:
$B(aq.)\rightleftharpoons B^{n+}(aq.)+n{e}^{-}$
$E^{\circ }=+4V$

Which of the following options is correct?

• A. Tendency to gain electrons does not depend upon $E^{\circ }$
• B. The reactant A has higher tendency to gain electrons than reactant B
• C. None of the above
• D. The reactant B has higher tendency to gain electrons than reactant A

Answer 1

The correct option is B The reactant A has higher tendency to gain electrons than reactant B

For Reaction 1 :
$A(aq.)\rightleftharpoons A^{n+}(aq.)+n{e}^{-}$
$E^{\circ }=+2V$

For reaction 2:
$B(aq.)\rightleftharpoons B^{n+}(aq.)+n{e}^{-}$
$E^{\circ }=+4V$

Since ,$E^{\circ }>0$ for both the reactions, the forward reactions for both the reactants are spontaneous.
Higher the electrode potential, higher is the tendency for the forward reaction to take place .
Consequently higher is the tendency to lose electrons.
Since, for reaction 1, $E^{\circ }$ value is less than $E^{\circ }$ value of reaction 2, reactant A will have a higher tendency to gain electrons as compared to reactant B