HYDROGEN OXYGEN FUEL CELL HALF REXN....

[Zebra]

okay guys.

In 2008 VCAA QUESTION 8 talks about a fuel cell where hydrogen and oxygen gas are reactants.
now, the first part asks you to deduce half eqs of the fuel cell.

It doesn't indicate whether this fuel cell is acidic or not (OR am I suppose to assume the fuel cell as acidic due to the ACIDIC ELECTROLYTE?).

Can someone tell me what the acidic/alkaline half rexns are ?

AND

Is the role of h2po4- electrolyte to maintain the electroneutrality in the cell?

thanks

[Mao]

>It doesn't indicate whether this fuel cell is acidic or not (OR am I suppose to assume the fuel cell as acidic due to the ACIDIC ELECTROLYTE?).
Yes it does. Read the stimulus. "...the phosphoric acid fuel cell, PAFC"

>Can someone tell me what the acidic/alkaline half rexns are ?
Balance equations as usual using KOHES, always give you the acidic half reaction.
Add base to neutralize the acid if you are in an alkaline environment.

>Is the role of h2po4- electrolyte to maintain the electroneutrality in the cell?
No. H+ counter-balances the electron flow. H2PO4- is simply a spectator ion. Do note however that it is an ion in solution, and therefore will be attracted towards the +ve electric potential (determined from the polarity of the electrodes)