Question

A galvanic cell is constructed by coupling a copper and a zinc electrode. If at $298K$:
$E_{C{u}^{2+}\left(aq\right)/Cu\left(s\right)}^{\circ }=+0.34V$
$E_{Z{n}^{2+}\left(aq\right)/Zn\left(s\right)}^{\circ }=-0.76V$

Which of the following is/are correct?

• A. $Z{n}^{2+}$ has a higher oxidising power.
• B. $C{u}^{2+}$ has a higher oxidising power.
• C. $E_{Zn\left(s\right)/Z{n}^{2+}\left(aq\right)}^{\circ }=+0.76V$
• D. $E_{Cu\left(s\right)/C{u}^{2+}\left(aq\right)}^{\circ }=+0.34V$

Answer 1

Answer: (B), (C)

$E_{Zn\left(s\right)/Z{n}^{2+}\left(aq\right)}^{\circ }=+0.76V$

Higher the reduction potential, greater is the oxidising power and vice versa.
Standard reduction potentials of zinc and copper are given.
Since,
$E_{C{u}^{2+}\left(aq\right)/Cu\left(s\right)}^{\circ }>E_{Z{n}^{2+}\left(aq\right)/Zn\left(s\right)}^{\circ }$
$C{u}^{2+}$ has a higher oxidising power and it gets reduced.

Reduction and oxidation potential for an electrode are equal in value and opposite in sign.
$\text{Oxidation potential}=-\text{Reduction potential}$
At standard conditions:
$\text{Standard Oxidation potential}=-\text{Standard Reduction potential}$
According to IUPAC convention, standard electrode potential is now expressed in terms of standard reduction potential