In a hydrogen-oxygen fuel cell operating under alkaline conditions, what is the product formed at the cathode during the reduction of oxygen?

In a hydrogen-oxygen fuel cell operating under alkaline conditions, the cathode is where the reduction of oxygen occurs. During this electrochemical reaction, oxygen (O2) from the air is reduced, and in the alkaline medium, this process involves the consumption of hydroxide ions (OH-) present in the solution. The overall reaction at the cathode can be represented as follows:

[ O_2 + 2H_2O + 4e^- \rightarrow 4OH^- ]

However, when considering the full operation of the fuel cell and net products, we also recognize that the reaction effectively converts oxygen and water into hydroxide ions. The immediate product of the cathode reaction is the formation of hydroxide ions, but considering the entire cell operation and typical representations, water is often highlighted as a significant product due to the overall balance of reactions involving hydrogen at the anode and the recombination processes.

Consequently, while hydroxide ions play a crucial role in the cathodic reaction, the primary and notable product associated with the operational mechanism of hydrogen-oxygen fuel cells, especially in terms of how the cell functions and the overall outputs, is water. Thus, water is the best representation of the end product formed as the result