Given for couple and for couple, where represents the standard state reduction potentials at pH = 7. — Electrochemistry Chemistry Question
Question
Given $E^\circ = 0.08 \text{ V}$ for $Fe^{3+}(\text{cyt b}) \| Fe^{2+}(\text{cyt b})$ couple and $E^\circ = 0.20 \text{ V}$ for $Fe^{3+}(\text{cyt c}_1) \| Fe^{2+}(\text{cyt c}_1)$ couple, where $E^\circ$ represents the standard state reduction potentials at pH = 7.0 at 25°C and cyt is an abbreviation for cytochromes. The value of $K_{eq}$ for the reaction $Fe^{3+}(\text{cyt c}_1) + Fe^{2+}(\text{cyt b}) \rightleftharpoons Fe^{2+}(\text{cyt c}_1) + Fe^{3+}(\text{cyt b})$ is ($2.303RT/F = 0.06$)
💡 Solution & Explanation
The cell potential for the reaction is $E^\circ_{cell} = E^\circ_{red}(\text{cathode}) - E^\circ_{red}(\text{anode}) = E^\circ(\text{cyt c}_1) - E^\circ(\text{cyt b}) = 0.20 - 0.08 = 0.12$ V. The relationship between standard potential and equilibrium constant is $\log K_{eq} = (n E^\circ) / 0.06$. Here $n = 1$. $\log K_{eq} = 0.12 / 0.06 = 2$. Thus, $K_{eq} = 10^2 = 100$. Therefore, correct answer is 0100.