According to the Gibbs free energy expression, an energy of Tx∆S will be converted into heat in the reaction that takes place in the Direct Methanol Fuel Cell and this energy will be unrecoverable. a) Calculate the Gibbs free energy of the reaction in Direct Methanol Fuel Cell for a temperature of 25 ° C? b) What is the maximum efficiency that can be achieved directly in the methyl alcohol fuel cell? c) What is the reversible cell voltage when operated directly in a methanol fuel cell in reversible conditions?
There are good data for thermodynamic properties in the NIST Chemistry Webbook. However, the DMFC has notoriously low efficiency and will be nowhere near the thermodynamic limit.
My first answer to b) is 100% - if the answer is any different, you are using the wrong definition of efficiency. But I guess someone expects you to calculate ΔG/ΔH, which is really a bad habit of textbooks.
Also, there is no such thing as reversible conditions in DMFCs - way too many side reactions at open circuit, especially the crossover flow. You can calculate the number, but keep in mind it will be mostly meaningless in real operation.
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