Fuel cells commonly use the reaction between hydrogen and oxygen to produce a voltage, with water being the only waste product. There are acid and alkaline fuel cells – Edexcel require you know the details of both, everyone else focuses solely on the alkaline hydrogen fuel cell.
Alkaline hydrogen fuel cell
- fuel cells require a constant fuel and oxygen supply to operate continuously
- the nature of the catalyst in the anode and cathode depends on the design of the fuel cell
- a newer type of this fuel cell uses a solid polymer electrolyte
- an advantage over batteries is that they don’t need recharging and the waste product is water
Acid hydrogen fuel cell
- the main disadvantage of the acid hydrogen fuel cell is that the acidic electrolyte increases the rate of corrosion of components of the cell that are in contact with it
Practice questions
In methanol fuel cell, the following reaction takes place at one of the electrodes.
CH3OH(g) + H2O(l) ⇾ HCOOH(aq) + 4H+(aq) + 4e–
(a) Which electrode is this reaction taking place at. Give a reason for your answer.
(b) Suggest a half equation for the reaction happening at the other electrode.
Answers
(a) anode; it is an oxidation reaction as electrons are released
(b) 2H+(aq) + ½O2(g) + 2e– ⇾ H2O(l)
Exam tip: in the question note that the half equation for the anode is producing H+ ions so this must be an example of an acid fuel cell