Electron transfer reactions oxygen production from water

Fig. 1 Schematic mechanism for the long-distance oxidation of DNA. Irradiation of the anthraquinone (AQ) and intersystem crossing (ISC) forms the triplet excited state (AQ 3), which is the species that accepts an electron from a DNA base (B) and leads to products. Electron transfer to the singlet excited state of the anthraquinone (AQ 1) leads only to back electron transfer. The anthraquinone radical anion (AQ ) formed in the electron transfer reaction is consumed by reaction with oxygen, which is reduced to superoxide. This process leaves a base radical cation (B+-, a hole ) in the DNA with no partner for annihilation, which provides time for it to hop through the DNA until it is trapped by water (usually at a GG step) to form a product, 7,8-dihydro-8-oxoguanine (8-OxoG)...

From the data in Appendix C, calculate the theoretical maximum EMF of a methane/oxygen fuel cell with an acidic electrolyte under standard conditions. Assume the products to be liquid water and aqueous CO2. [Hint You need to know the number of electrons transferred per mole CH4 consumed. Write a balanced equation for the net reaction, and obtain the number of electrons from Eq. 15.47.] [Answer 1.05 V.]... 

---