네른스트 식. Fe | Fe^2+ (1.500 M) || Au^3+ (0.00400 M) | Au

네른스트 식. Fe | Fe^2+ (1.500 M) || Au^3+ (0.00400 M) | Au

 

 

Find the emf of the cell described by the cell diagram

Fe | Fe^2+ (1.500 M) || Au^3+ (0.00400 M) | Au

A) 1.99 V

B) 1.89 V

C) 1.94 V

D) 1.66 V

E) 1.91 V

 

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> 산화: Fe → Fe^2+ + 2e^-

> 환원: Au^3+ + 3e^- → Au

 

 

> 산화: 3Fe → 3Fe^2+ + 6e^-

> 환원: 2Au^3+ + 6e^- → 2Au

---> n = 6

 

 

> 전체: 3Fe(s) + 2Au^3+(aq) → 3Fe^2+(aq) + 2Au(s)

Q = [Fe^2+]^3 / [Au^3+]^2

= (1.500)^3 / (0.00400)^2

 

 

 

> E°(Fe^2+/Fe(s)) = –0.44 V

> E°(Au^3+/Au(s)) = +1.52 V

 

 

E°_cell = E°_red – E°_red

= (환원된 물질의 표준환원전위) – (산화된 물질의 표준환원전위)

( 참고 https://ywpop.tistory.com/4558 )

 

= (+1.52) – (–0.44) = +1.96 V

 

 

 

Nernst 식

E = E° – (0.0592 V / n) × logQ

( 참고 https://ywpop.tistory.com/2900 )

 

= (+1.96) – (0.0592 / 6) × log( (1.500)^3 / (0.00400)^2 )

= +1.91 V

 

 

 

답: E) 1.91 V

 

 

 

 

[ 관련 예제 https://ywpop.tistory.com/19955 ] 네른스트 식. Cr | Cr^3+ (0.1 M) || Fe^2+ (0.01 M) | Fe

 

 

 

[키워드] redox 3Fe + 2Au^3+ → 3Fe^2+ + 2Au, redox Fe + Au^3+, redox Au^3+ + Fe