Redox II

Alkaline - hydrogen fuel cell equations

H2 (g) + 2OH– (aq)  →  2H2O (l) +  2e–  (negative electrode)

O2 (g) +  2H2O  +  4e– →  4OH– (aq) (positive electrode)   

2H2 (g) + O2 (g)  →   2H2O (l)           Eθ = +1.23 V

Suggest why the e cell value for a hydrogen fuel cell operating in acid and alkaline conditions are identical (1)

As same reaction

One reason (other then cost implications) why platinum electrode are made by coating porous material with platinum rather than using platinum rods (1)

 

To increase surface area, and provide more active sites

Platinum cataclysms both the direct combination of hydrogen with oxygen and the reactions in the fuel cell. By considering the way the catalyst lowers the EA, what are two similarities to these processes (2)

Both involve breaking bonds

Both involve active sites on catalyst

What is considered to be the main advantage of hydrogen as a fuel, keep in mind hydrogen is obtained from fossil fuels (1)

Water as only product

Explain the main advantage of using a fuel cell over direct combustion of hydrogen (2)

More efficient, 70% more, As it Produces electricity directly

Less heat loss, as it releases energy in a more controlled manner

 

A disadvantage of using hydrogen duel cell compared with direct combustion of hydrogen (1)

Expensive

Cost of catalyst

Short life span