Question

The standard emf of the cell $Zn|Z{n}^{2+}||A{g}^{+}|Ag$ is $1.56V$. If the standard reduction potential of $Ag$ is $0.8V$, the standard oxidation potential of $Zn$ is

• A. $-0.76V$
• B. $+0.76V$
• C. $-2.36V$
• D. $+2.36V$

Answer 1

Answer: (B)

For the cell,
$Zn|Z{n}^{2+}||A{g}^{+}|Ag$
$E_{cell}^{{}^{\circ }}=E_{cathode}^{\circ }=E_{anode}^{\circ }$
$1.56V=E_{A{g}^{+}/Ag}^{{}^{\circ }}-E_{Z{n}^{2+}/Zn}^{{}^{\circ }}$
$1.56V=0.8V-E_{Z{n}^{2+}/Zn}^{{}^{\circ }}$
$E_{Z{n}^{2+}/Zn}^{{}^{\circ }}$ = - 0.76{\,} V
$\therefore E_{Z{n}^{2+}/Zn}^{{}^{\circ }}=+0.76V$