Question

ome fuel cells are powered by hydrogen. Scientists are looking into the decomposition of water (H2O) to make hydrogen fuel with the help of the Sun’s energy. What challenge do scientists face with this task?

Answer 1

Answer is: Decomposing water requires a high activation energy.

Electrolysis of water is the decomposition reaction, because from one molecule (water) two molecules (hydrogen and oxygen) are produced. Water is separeted into two molecules:

Reaction of reduction at cathode: 2H⁺(aq) + 2e⁻ → H₂(g).

Reaction of oxidation at anode: 2H₂O(l) → O₂(g) + 4H⁺(aq) + 4e⁻.