Question

The standard reduction potentials of Zn and Ag in water at 298 K ate, $Z{n}^{+2}+2e^{-}\rightleftharpoons Zn;E^o=-0.76V$ and $A{g}^{+}+e^{-}\rightleftharpoons Ag;E^o=+0.80V$. Which of the following reactions take place?

• A. $Z{n}^{+2}\left(aq\right)+2Ag\left(s\right)\to 2A{g}^{+}\left(aq\right)+Zn\left(s\right)$
• B. $Zn\left(s\right)+2A{g}^{+}\left(aq\right)\to Z{n}^{+2}\left(aq\right)+2Ag\left(s\right)$
• C. $Z{n}^{+2}\left(aq\right)+A{g}^{+}\left(aq\right)\to Zn\left(s\right)\left(aq\right)+Ag\left(s\right)$
• D. $Zn\left(s\right)+Ag\left(s\right)\to Z{n}^{+2}\left(aq\right)+A{g}^{+}\left(aq\right)$

Answer 1

The correct option is B $Zn\left(s\right)+2A{g}^{+}\left(aq\right)\to Z{n}^{+2}\left(aq\right)+2Ag\left(s\right)$

The reaction $Zn\left(s\right)+2A{g}^{+}\left(aq\right)\to Z{n}^{+2}\left(aq\right)+2Ag\left(s\right)$ is spontaneous and takes place.
Note: The standard reduction potential of silver is greater than the standard reduction potential of zinc.
Hence, Ag(I) is stronger oxidizing agent than Zn(II). Hence, the reduction of Ag(I) to Ag and the oxidation of Zn to Zn(II) takes place.