[Cd2+] = 0.96 M, [H+] = 0.13 M, PH2 = 0.83 atm

[Cd2+] = 0.96 M, [H+] = 0.13 M, PH2 = 0.83 atm

 

 

What is the emf of a galvanic cell consisting of a Cd^2+/Cd half-cell and a Pt/H^+/H2 half-cell at the following concentrations and pressures?

[Cd^2+] = 0.96 M, [H^+] = 0.13 M, P_H2 = 0.83 atm

 

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표준 환원 전위

Cd^2+ + 2e^- → Cd ... E = -0.40 V

2H^+ + 2e^- → H2 ... E = 0.00 V

( 참고 https://ywpop.tistory.com/7027 )

 

 

전지 반응

Cd(s) + 2H^+(aq) → Cd^2+(aq) + H2(g)

 

 

표준 기전력

E°cell = E°red(환원전극) - E°red(산화전극)

= (환원된 물질의 표준환원전위) – (산화된 물질의 표준환원전위)

= (0.00) - (-0.40) = +0.40 V

 

 

반응비(reaction quotient)

Q = [Cd^2+] P_H2 / [H^+]^2

= (0.96) (0.83) / (0.13)^2 = 47.1479

 

 

네른스트 식. Nernst equation

E = E° - (0.0592 V / n) × logQ

( 식 설명 https://ywpop.tistory.com/2900 )

= (+0.40 V) - (0.0592 V / 2) × log(47.1479)

= +0.35 V

 

 

답: +0.35 V