Question

The positive value of the standard electrode potential of $C{u}^{2+}/Cu$ indicates that ___.

• A. this redox couple is a stronger oxidising agent than $H^{+}/H_2$ .
• B. this redox couple is a stronger reducing agent than the $H^{+}/H_2$ couple.
• C. Cu cannot displace $H_2$ from acid.
• D. Cu can displace $H_2$ from acid.

Answer 1

Answer: (A), (C)

Cu cannot displace $H_2$ from acid.

Oxidizing agent and reducing agent

Oxidising agents:
These are those species that oxidises other species and itself gets reduced.
Thus, higher the reduction potential, more is the tendency to get reduced and better will be its oxidising power and better will be the oxidizing agent.

Reducing agent:
These are the species that reduces other and itself gets oxidised.
Thus, lesser is the reduction potential, more is the tendency to get oxidised and more will be its reducing power and better will be the reducing agent.

Comparing the standard reduction

$E^0{}_{C{u}^{2+}/Cu}=0.34V$
$E^0{}_{H^{+}/H_2}=0.0V$

Reduction potential of $C{u}^{2+}/Cu$ couple is more, thus tendency of $C{u}^{2+}$ to get reduced is more which signifies that it is a better oxidising agent than $H^{+}/H_2$ couple.

$Metalreactivity\alpha \frac{1}{\text{standard reduction potential}}$

Since $E^0{}_{C{u}^{2+}/Cu}>E^0{}_{H^{+}/H_2}$,
the metal reactivity of Cu is less, due to which it cannot displace $H_2$ from acid.

Hence, the correct options are (B) and (D).