Q. Aluminium displaces hydrogen from dilute HCl whereas silver does not. The emf of Acell prepared by combining $Al/\ {Al}^{3 +}$ and $Ag\ /\ {Ag}^{+}$ is 2.46 V. The reduction potential of silver electrode is +0.80 V. The reduction potential of aluminium electrode is
A) +1.66 V
B) -3.26 V
C) 3.26 V
D) -1.66 V
Explanation
(d)
$E_{cell}^{{^\circ}} = \ E_{cathode}^{{^\circ}}\ - \ \ E_{anode}^{{^\circ}}$
∴ $2.46\ = ( + 0.80) - \ E_{{Al}^{3 +}\ /Al}^{{^\circ}}$
Or $E_{{Al}^{3 +}\ /Al}^{{^\circ}}\ = \ 0.80\ –\ 2.46\ = \ - \ 1.66\ V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.