There is great current interest in developing fuel cells based on the reaction, 2CH3OH(l) + 3O2(g) → — Electrochemistry / Thermodynamics Chemistry Question
Problem Context
There is great current interest in developing fuel cells based on the reaction,
2CH3OH(l) + 3O2(g) → 2CO2(g) + 4H2O(l)
Write a balanced equation for the half-reaction that occurs in acid solution for such a fuel cell at the;
i. anode.
Model Answer
CH3OH + H2O → CO2 + 6H+ + 6e–
ii. cathode.
Model Answer
O2 + 4H+ + 4e– → 2H2O
If the E˚ value for the cell reaction is 1.21 V, calculate the value of ∆G˚.
Model Answer
ΔGo = –nFEo = –(12 mol)(96500 J/V⋅mol)(1.21 V) = –1.40×103 kJ
The E˚ value for the O2(g) half reaction is 1.23 V in 1 M H+, calculate the E˚ value expected in 1 M OH–.
Model Answer
Use the Nernst equation:
so,
= 0.40 V
State two advantages of carrying out this reaction in a fuel cell rather than burning methanol and converting the heat into electricity.
Model Answer
- No wasted heat. 2. No energy lost during conversion.