Question

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

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

Answer 1

The correct option is D create potential difference between the two electrodes.

In hydrogen-oxygen fuel cell, following reactions take place to create potential difference between the two electrodes.
In fuel cell, the chemical energy of combustion of fuels like $H_2,C{H}_4,C{H}_{3}OH$ etc. are directly coverted into electrical energy.
At the anode
$H_2\left(g\right)+2O{H}^{-}\left(aq\right)\to 2H_{2}O\left(l\right)+2e^{-}$

At the cathode
$O_2\left(g\right)+2H_{2}O\left(l\right)+4e^{-}\to 4O{H}^{-}\left(aq\right)$

Overall reaction is
$2H_2\left(g\right)+O_2\left(g\right)\to 2H_{2}O\left(l\right)$