Question

In fuel cells, the reaction that takes place at the anode is:

• A. $H_2\left(g\right)+2O{H}^{-}\left(aq\right)\to 2H_{2}O\left(l\right)+2e^{-}$
• B. $2H^{+}+2e^{-}\to H_2$
• C. $O_2\left(g\right)+2H_{2}O\left(l\right)+4e^{-}\to 4O{H}^{-}\left(aq\right)$
• D. $4O{H}^{-}\to O_2+2H_{2}O+4e^{-}$

Answer 1

Answer: (A)

For a fuel cell to work, it needs hydrogen $\left(H_2\right)$ and oxygen $\left(O_2\right)$.

The hydrogen enters the fuel cell at the anode. A chemical reaction strips the hydrogen molecules of their electrons and the atoms become ionized to form $H^{+}$. The electrons travel through wires to provide a current to do work.

The oxygen enters the cathode, usually from the air. The oxygen picks up the electrons that have completed their circuit. The oxygen then combines with the ionized hydrogen atoms $\left(H^{+}\right)$, and water $\left(H_{2}O\right)$ is formed as the waste product which exits in the fuel cell.

The electrolyte plays an essential role as well. It only allows the appropriate ions to pass between the anode and the cathode. If other ions were allowed to flow between the anode and cathode, the chemical reactions within the cell would be disrupted.

Therefore, the reaction at anode is $H_2\left(g\right)+2O{H}^{-}\left(aq\right)\to 2H_{2}O\left(l\right)+2e^{-}$.

Option A is correct.