The standard half-cell reduction potential for Ag + ∣ Ag is 0.7991 V at 2 5 ∘ C . Given the experimental value K s p = 1.56 × 1 0 − 10 for AgCl , calculate the standard half-cell reduction potential

Question

The standard half-cell reduction potential for Ag + ∣ Ag is 0.7991 V at 2 5 ∘ C . Given the experimental value K s p ​ = 1.56 × 1 0 − 10 for AgCl , calculate the standard half-cell reduction potential for the Ag ∣ AgCl electrode.

TestHub · Accepted Answer

For the desired reaction, AgCl + 1 e − → Ag + Cl − , E ∘ = ( 1 ) F − Δ r ​ G ∘ ​ The needed Δ r ​ G ∘ can be obtained by adding the values of Δ r ​ G ∘ for the reactions ​ Ag + + 1 e − → Ag ; Δ G ∘ = − n F E ∘ AgCl → Ag + + Cl − ; Δ G ∘ = − RT ln K s p ​ , giving Δ r ​ G ∘ = − ( 1 mol ) ( 9.648 × 1 0 4 J mol − 1 V − 1 ) ( 0.7991 V ) − ( 8.314 JK − 1 mol − 1 ) ( 298 K ) ln ( 1.56 × 1 0 − 10 ) = − 77.10 kJ + 55.95 kJ = − 21.15 kJ ​ The potential is E ∘ = ( 1 ) ( 96.485 ) − ( − 21.15 ) ​ = + 0.2192 V .

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