Question

The half cell reactions with their appropriate standard reduction potentials are

(i) $Pb^{2 +} + 2e^{-} \rightarrow Pb;(Eº = - 0.13V)$

(ii) $Ag^{+} + e^{-} \rightarrow Ag;(Eº = + 0.80V)$

Based on the above data, which of the following reactions will take place?

• A. $Pb^{2 +} + 2Ag \rightarrow 2Ag^{+} + Pb$
• B. $2Ag + Pb \rightarrow 2Ag^{+} + Pb^{2 +}$
• C. $2Ag^{+} + Pb \rightarrow Pb^{2 +} + 2Ag$
• D. $Pb^{2 +} + 2Ag^{+} \rightarrow Pb + Ag$

Answer 1

Answer: (C)

$2Ag^{+} + Pb \rightarrow Pb^{2 +} + 2Ag$

Answer 2

At cathode: $Ag^{+} + e^{-} \rightarrow Ag;Eº = + 0.80V$

At anode: $Pb \rightarrow Pb^{2 +} + 2e^{-};Eº = + 0.13V$

$Eº_{cell} = E_{cathode} - E_{anode} = 0.80 - 0.13 = 0.67V$

Hence the reaction will be

$2Ag^{+}Pb \rightarrow Pb^{2 +} + 2Ag$