Nernst 식. [Fe^2+] = 10^(-3) M, P_O2 = 0.1 atm, pH = 3

Nernst 식. [Fe^2+] = 10^(-3) M, P_O2 = 0.1 atm, pH = 3

 

 

Consider the following cell reaction:

2Fe(s) + O2(g) + 4H^+(aq) → 2Fe^2+(aq) + 2H2O(l) ... E° = 1.67 V

At [Fe^2+] = 10^(-3) M, P_O2 = 0.1 atm and pH = 3,

the cell potential at 25℃ is

 

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2Fe(s) + O2(g) + 4H^+(aq) → 2Fe^2+(aq) + 2H2O(l)

> 산화: 2Fe(s) → 2Fe^2+(aq) + 4e^-

> 환원: O2(g) + 4H^+(aq) + 4e^- → 2H2O(l)

( 참고 https://ywpop.tistory.com/2896 )

---> n = 4

 

 

 

[H^+] = 10^(-pH) M = 10^(-3) M

 

 

 

Q = [Fe^2+]^2 / {P_O2 [H^+]^4}

= (10^(-3))^2 / ( (0.1) (10^(-3))^4 )

= 10^7

 

 

 

Nernst 식

E = E° – (0.0592 V / n) logQ

( 참고 https://ywpop.tistory.com/2900 )

 

= (1.67) – (0.0592 / 4) log(10^7)

= 1.5664 V

 

 

 

답: 1.57 V

 

 

 

 

[ 관련 예제 https://ywpop.tistory.com/4423 ] Nernst 식. [Fe^3+] = 3.50 M H2 = 0.95 atm [Fe^2+] = 0.0010 M pH 4.00

 

 

 

[키워드] Nernst 식에서 기체의 압력 기준문서, Nernst 식에서 기체의 압력 사전