Question

In a hydrogen - oxygen fuel cell, combustion of hydrogen occurs to :

• A. Produce high purity water
• B. Create potential difference between the two electrodes
• C. Generate heat
• D. Remove adsorbed oxygen from electrode surfaces

Answer 1

Answer: (B)

Create potential difference between the two electrodes

Answer 2

In hydrogen-oxygen fuel cell, following reactions take place to create potential difference between the two electrodes.
$2H_{2}\left(g\right)+4OH^{-}\left(aq\right) \rightarrow 4H_{2}O\left(l\right)+4e^{-}$
$\frac{O_{2}\left(g\right)+2H_{2}O\left(l\right)+4e^{-}\rightarrow4OH^{-}\left(aq\right)}{Overall reaction=2H_{2}\left(g\right)+O_{2}\left(g\right)\rightarrow2H_{2}O\left(l\right)}$
the net reaction is the same as burning (combustion) of hydrogen to form water.