PUC Karnataka Science Class 12Department of Pre-University Education, Karnataka
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The cell in which the following reactions occurs: 2Fe3+ (aq) + 2I– (aq) —> 2Fe2+ (aq) - PUC Karnataka Science Class 12 - Chemistry

ConceptRelation Between Gibbs Energy Change and Emf of a Cell

Question

The cell in which the following reactions occurs: 2Fe3+ (aq) + 2I– (aq) —> 2Fe2+ (aq) +I2 (s) has E°cell=0.236 V at 298 K. Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.

Solution

Here, n = 2, E_"cell"^theta = 0.236  T = 298 K

We know that:

triangle_rG^(theta) = -nFE_("cell")^theta

= −2 × 96487 × 0.236

= −45541.864 J mol−1

= −45.54 kJ mol−1

Again, triangle_rG^theta = −2.303RT log Kc

=>log K_c = (triangle_rG^theta)/(2.303 RT)

= (-45.54xx10^3)/2.303xx8.314xx 298

= 7.981

Kc = Antilog (7.981)

= 9.57 × 107

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Solution The cell in which the following reactions occurs: 2Fe3+ (aq) + 2I– (aq) —> 2Fe2+ (aq) Concept: Relation Between Gibbs Energy Change and Emf of a Cell.
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