by ykanazawa1999

Question by Nabz: How does the reaction of hydrogen and oxygen to produce energy in a fuel cell differ from direct combustion?
A. It is much easier to control the hydrogen and oxygen during direct combustion than during their reaction in a fuel cell.
B. Much less heat energy is produced in a fuel cell than via direct combustion of hydrogen and oxygen.
C. In the fuel cell, there is an oxidation-reduction reaction between hydrogen and oxygen. In the direct combustion of hydrogen and oxygen, there is no such reaction.
D. The direct combustion of hydrogen and oxygen produces several different products, whereas the fuel cell produces only water.

Best answer:

Answer by pisgahchemist
2H2 + O2 –> 2H2O …. The same reaction occurs in both combustion and a fuel cell.

None of your answers are particularly satisfying, even the one that the question writer thinks is correct, which is (B).

While it is true that much less heat is produced in the fuel cell, the question implies that there is less energy change in the fuel cell. That simply isn’t true. The change in energy is the same regardless of whether the reaction occurs in an instant, as in the explosive combustion of H2 and O2, or over a much longer time, as with the exchange of protons and the corresponding movement of electrons, in a fuel cell. The only difference is the time interval over which the chemical change occurs, the rate of reaction.

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