In the respiratory electron transport chain, electrons are transferred spontaneously from a cytochrome of lower reduction potential to one of higher reduction potential. Three cytochromes A, B and C h

Question

In the respiratory electron transport chain, electrons are transferred spontaneously from a cytochrome of lower reduction potential to one of higher reduction potential. Three cytochromes A, B and C have the following standard reduction potentials (at physiological conditions):

$E^{o} = (A^{3 +}$ / $A^{2 +}) = + 0.12 V$

$E^{o} = (B^{3 +}$ / $B^{2 +}) = + 0.31 V$

$E^{o} = (C^{3 +}$ / $C^{2 +}) = 0.44 V$

Electrons are transferred from the cytochrome with the lowest reduction potential to the one with the highest reduction potential. If one electron is transferred from the first cytochrome to the last cytochrome, calculate the value of |ΔG⁰ | in kJ mol^-1. (Use 1F = 96500 C)

TestHub · Accepted Answer

Solution. Lowest potential = A , highest potential = C Δ E o = E C ​ o − E A ​ o = 0.44 − 0.12 = 0.32 V For n = 1 : Δ G o = − n F Δ E o = − ( 1 ) ( 96500 ) ( 0.32 ) = − 30880 J mol − 1 ∣ Δ G ∘ ∣ = 30.88 kJ / mol

Chemistry - Electrochemistry Question with Solution | TestHub

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