chemistry inorganic

Question

Using the Nernst equation, what is the potential for the O2 reduction at 25 °C,

pH = 7 and p(O2) = 0.20 atm, given that Eo(O2/H2O) = 1.23 V?

Answer 1

E = E₀ - RT/(n_eF) * lnQ where Q in this case is the K expression with the initial values for the reaction O₂ + 4e^- + 4H⁺ → 2H₂O

Q = 1/(P_O2[H⁺]⁴) = (.20 atm)^-1(10^-7 M)^-4

E = 1.23V - (8.314 J /mK)(298K)/((4 moles)(96485 C/mole)) * ln(Q)

I'll leave the details to you. Make sure you understand the units, the Q, and the reduction potential equation. It makes sense that the lower the P_O2 and the lower the [H⁺], the less chemical potential there is for the reaction to go forward.