At 298 K , the standard electrode potentials of Cu 2 + / Cu , Zn 2 + / Zn , Fe 2 + / Fe and Ag + / Ag are 0 . 34 V , - 0 . 76 V , - 0 . 44 V and 0 . 80 V , respectively. On the basis of standard electrode potential, predict which of the following reaction cannot occur?

Question

Aicharya · Accepted Answer

The given standard reduction potentials of $Zn, Cu, Ag$ and $Fe$ are;

$E °_{\frac{{Zn}^{2 +}}{Zn}} = - 0.76 V, E °_{\frac{{Cu}^{2 +}}{cu}} = 0.34 V E °_{\frac{{Ag}^{+}}{Ag}} = 0.80 V, and E °_{\frac{{Fe}^{2 +}}{Fe}} = - 0.44 V$

The condition for reaction to occur, $E °_{Cell} = {(E °_{SRP})}_{reduction reaction} - {(E °_{SRP})}_{oxidation reaction}$ must have the positive value.

$(A) {Cu}^{2 +} (aq) + Fe \to Cu + {Fe}^{2 +} (aq)$

$E °_{Cell} = 0.34 + 0.44 E °_{Cell} = 0.78 V$

$(B) Zn + {Fe}^{2 +} (aq) \to {Zn}^{2 +} (aq) + Fe$

$E °_{Cell} = - 0.44 + 0.76 E °_{Cell} = + 0.32 V$

$(C) {Cu}^{2 +} (aq) + 2 Ag \to 2 {Ag}^{+} (aq) + Cu$

$E °_{Cell} = 0.34 - 0.80 E °_{Cell} = - 0.46 V$

$(D) Zn + {Cu}^{2 +} (aq) \to {Zn}^{2 +} (aq) + Cu$

$E °_{Cell} = 0.34 + 0.76 E °_{Cell} = + 1.10 V$

Hence, the reaction given in $C$ option is not possible.

At 298 K , the standard electrode potentials of Cu 2 + / Cu , Zn 2 + / Zn , Fe 2 + / Fe and Ag + / Ag are 0 …

Solution