Some bacteria get their energy from reduction of CO2 to CH4 by H2.

1. How many electrons are required to reduce CO2 to CH4?
2. Calculate the G for formation of methane based on the two standard reduction potential of -0.171V for reduction of CO2 to CH4 and -0.414V for reduction of H+ to H2.

1 answer

4H2 + CO2 ==> CH4 + 2H2O
You have 2H2 ==> 4H^+ + 4e
and 2H2 + 4e ==> 4H^-
so (a) is 4 electrons.
If you add -.171 + 0.414 = ?
Then dG = -nEF to calculate dG.