Standard electrode potentials for a few half cells are mentioned below: Which one of the following cells gives the most negative value of ? [2025]

Question

Standard electrode potentials for a few half cells are mentioned below:

$E_{{Cu}^{2 +} / Cu}^{\circ} = 0.34 V, E_{{Zn}^{2 +} / Zn}^{\circ} = - 0.76 V$

$E_{{Ag}^{+} / Ag}^{\circ} = 0.80 V, E_{{Mg}^{2 +} / Mg}^{\circ} = - 2.37 V$

Which one of the following cells gives the most negative value of $Δ G °$ ? [2025]

Smart Achievers · Accepted Answer

(1)

Cell Representation	$E_{cell}^{\circ} = E_{cathode}^{\circ} - E_{anode}^{\circ}$	$Δ G_{cell}^{\circ} = - n F E_{cell}^{\circ}$
$Zn \| {Zn}^{2 +} (1 M) ‖ {Ag}^{+} (1 M) \| Ag$	$E_{cell}^{\circ} = E_{{Ag}^{+} / Ag}^{\circ} - E_{{Zn}^{2 +} / Zn}^{\circ} = [0.80 - (- 0.76)] V = 1.56 V$	$Δ G_{cell}^{\circ} = - 2 F \times 1.56 = - 3.12 F$
$Cu \| {Cu}^{2 +} (1 M) ‖ {Ag}^{+} (1 M) \| Ag$	$E_{cell}^{\circ} = E_{{Ag}^{+} / Ag}^{\circ} - E_{{Cu}^{2 +} / Cu}^{\circ} = [0.80 - 0.34] V = 0.46 V$	$Δ G_{cell}^{\circ} = - 2 F \times 0.46 = - 0.92 F$
$Zn \| {Zn}^{2 +} (1 M) ‖ {Mg}^{2 +} (1 M) \| Ag$	$E_{cell}^{\circ} = E_{{Mg}^{2 +} / Mg}^{\circ} - E_{{Zn}^{2 +} / Zn}^{\circ} = [- 2.37 - (- 0.76)] V = - 1.61 V$	$Δ G_{cell}^{\circ} = - 2 F \times (- 1.61) = 3.22 F$
$Ag \| {Ag}^{+} (1 M) ‖ {Mg}^{2 +} (1 M) \| Mg$	$E_{cell}^{\circ} = E_{{Mg}^{2 +} / Mg}^{\circ} - E_{{Ag}^{+} / Ag}^{\circ} = [- 2.37 - 0.80] V = - 3.17 V$	$Δ G_{cell}^{\circ} = - 2 F \times (- 3.17) = 6.34 F$

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