Question 4

Calculate the standard cell potentials of galvanic cells in which the following reactions take place:

(i) 2Cr(s) + 3Cd²⁺(aq) → 2Cr³⁺(aq) + 3Cd

(ii) Fe²⁺(aq) + Ag+(aq) → Fe³⁺(aq) + Ag(s)

Calculate the ΔrG^ø¸ and equilibrium constant of the reactions.

Answer

(i) E^ø _{Cr³⁺ / Cr}= - 0.74 V

E^ø _{Cd²⁺ / Cd}= - 0.40 V

The galvanic cell of the given reaction is depicted as:

Now, the standard cell potential is

E^ø = E^ø_R- E^ø_L

= -0.40 - (-0.74)

= + 0.34 V

ΔrG^ø = -nFE^ø_cell

In the given equation,

n = 6

F = 96487 C mol ^{- 1}

E^ø_cell= +0.34 V

Then, ΔrG^ø= - 6 × 96487 C mol^{- 1} × 0.34 V

= - 196833.48 CV mol ^{- 1}

= - 196833.48 J mol^{- 1}

= - 196.83 kJ mol^{- 1}

Again,

ΔrG^ø= - RT ln K

= 34.496

K = antilog (34.496)

= 3.13 × 10³⁴

(ii) E^ø _{Fe³⁺ / Fe²⁺}= 0.77 V

E^ø _{Ag⁺ / Ag}= 0.80 V

The galvanic cell of the given reaction is depicted as:

Now, the standard cell potential is

E^ø = E^ø_R- E^ø_L

= 0.80 - 0.77

= 0.03 L

Here, n = 1.

Then, ΔrG^ø = -nFE^ø_cell

= - 1 × 96487 C mol^{- 1} × 0.03 V

= - 2894.61 J mol^{- 1}

= - 2.89 kJ mol^{- 1}

Again, ΔrG^ø= - 2.303 RT ln K

= 0.5073

K = antilog (0.5073)

= 3.2 (approximately)

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Govind yadav 2019-10-16 11:54:14

Very helpful to me

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Calculate the standard cell potentials of galvanic cells in which the following reactions take place:

(i) 2Cr(s) + 3Cd²⁺(aq) → 2Cr³⁺(aq) + 3Cd

(ii) Fe²⁺(aq) + Ag+(aq) → Fe³⁺(aq) + Ag(s)

Calculate the ΔrG^ø¸ and equilibrium constant of the reactions.

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Calculate the standard cell potentials of galvanic cells in which the following reactions take place: (i) 2Cr(s) + 3Cd2+(aq) → 2Cr3+(aq) + 3Cd (ii) Fe2+(aq) + Ag+(aq) → Fe3+(aq) + Ag(s) Calculate the ΔrGø¸ and equilibrium constant of the reactions.

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Calculate the standard cell potentials of galvanic cells in which the following reactions take place:

(i) 2Cr(s) + 3Cd²⁺(aq) → 2Cr³⁺(aq) + 3Cd

(ii) Fe²⁺(aq) + Ag+(aq) → Fe³⁺(aq) + Ag(s)

Calculate the ΔrG^ø¸ and equilibrium constant of the reactions.