Question

Which of the following statement is true?
$A{g}^{+}\left(aq\right)+e^{-}\to Ag\left(s\right);E^0=0.80V$
$C{u}^{2+}\left(aq\right)+2e^{-}\to Cu\left(s\right);E^0=0.34V$

• A. $Cu$ displace $Ag$ from $AgN{O}_3$
• B. $AgN{O}_3$ solution cannot be stored in $Cu$ vessel
• C. Both (a) and (c)
• D. $CuS{O}_4$ solution cannot be stored in $Ag$ vessel

Answer 1

The correct option is C Both (a) and (c)

Standard reduction potentials (SRP) of the half cell electrodes are calculated and arranged in a series of increasing order which is known as electrochemical series.
The standard electrode potential of $H^{+}/H_2$ couple is zero.

Here, a negative $E^0$ signifies that it has high tendency to get oxidised and the redox couple is a stronger reducing agent than the $H^{+}/H_2$ couple.

A positive $E^0$ signifies that it has high tendency to get reduced and the redox couple is a stronger oxidising agent than the $H^{+}/H_2$ couple.

If the given reaction :
$Cu\left(s\right)+2AgN{O}_3\to Cu(N{O}_3{)}_2+2Ag(s)$
takes place then we cannot store $AgN{O}_3$ solution in $Cu$ vessel.
$E_{cell}^0=\text{SRP cathode- SRP anode}$
$E_{cell}^0=E_{A{g}^{+}/Ag}^0-E_{C{u}^{2+}/Cu}^0{E}_{cell}^0=(0.8-0.34)V{E}_{cell}^0=0.46V$
Since $E_{cell}^0>0$, reaction takes place and copper displaces silver from silver nitrate. Hence, we cannot store $AgN{O}_3$ solution in a copper vessel.
$E^0$ value of $Ag$ is high so it cannot displace $Cu$ from $CuS{O}_4$solution. Also, $E_{cell}^0$ value for the reverse reaction is negative and hence copper sulphate can be stored in $Ag$ vessel.