Answer:
E°cell = - 1.3575 V
This reaction is spontaneous in the reverse direction
Explanation:
The given cell reaction:
Cr³⁺(1.32 × 10⁻³ M) + Fe²⁺(aq) → Cr²⁺(aq) + Fe³⁺(1.14 M)
The given Gibbs free energy: ΔG = 131 kJ = 131 × 10³ J (∵ 1 kJ = 10³ J)
As we know,
ΔG = - n F E°cell
Here, n - the number of moles of electrons transferred = 1
F - Faraday constant = 96500
E°cell - cell potential = ?
![\therefore E^{\circ }_{cell} = -\frac{\Delta G}{n \: F} = -\frac{131\times 10^{3}\, J}{1\, mol\times96500 \, C.mol^{-1}}](https://tex.z-dn.net/?f=%5Ctherefore%20E%5E%7B%5Ccirc%20%7D_%7Bcell%7D%20%3D%20-%5Cfrac%7B%5CDelta%20G%7D%7Bn%20%5C%3A%20F%7D%20%3D%20-%5Cfrac%7B131%5Ctimes%2010%5E%7B3%7D%5C%2C%20J%7D%7B1%5C%2C%20mol%5Ctimes96500%20%5C%2C%20C.mol%5E%7B-1%7D%7D)
![\Rightarrow E^{\circ }_{cell} = -1.3575\, V](https://tex.z-dn.net/?f=%5CRightarrow%20E%5E%7B%5Ccirc%20%7D_%7Bcell%7D%20%3D%20-1.3575%5C%2C%20V)
<u>For a given chemical reaction if-</u>
1. ΔG = negative and E°cell = positive
⇒ <em>The reaction is spontaneous and proceeds spontaneously in the forward direction.</em>
2. ΔG = positive and E°cell = negative
⇒ <em>The reaction is non-spontaneous and proceeds spontaneously in the reverse direction.</em>
<u>Since, for this chemical reaction: </u>
Cr³⁺(1.32 × 10⁻³ M) + Fe²⁺(aq) → Cr²⁺(aq) + Fe³⁺(1.14 M)
ΔG = + 131 × 10³ J ⇒ positive
and, E°cell = - 1.3575 V ⇒ negative
<u>Therefore, this reaction is spontaneous in the reverse direction.</u>