Lesson 5: Fuel cells Flashcards
What are fuel cells?
- Fuel cells include a reaction between H2 and O2 to produce an electric current.
What happens to the electrons that the Hydrogen molecules split into?
- Electrons pass through the wire and generate the electric current.
What is the half- equation for hydrogen at the negative electrode?
2H₂ —> 4H⁺ +4e⁻
What is the half equation at the positive electrode?
O₂ + 4H⁺ + 4e⁻ –> 2H₂O
What is the overall reaction in a fuel cell?
2H₂ + O₂ –> 2H₂O
Hydrogen has been oxidised to produce water…
What is the effect of the fuel being oxidised?
- Fuel oxidised electrochemically within the fuel cell to produce a potential difference.
How long will hydrogen cells produce electricity for?
How long will rechargable batteries produce electricity for?
1.) For as long as you provide hydrogen.
2.) Rechargable batteries run out and need to be recharged.
Do hydrogen cells get less efficient the more they run?
How about rechargable batteries?
1.) Hydrogen cells donnot get less efficient the longer they run.
2.) Rechargable batteries store less electricity the more charging cycles they go through/ will need to be replaced.
How is the H₂O produced from hydrogen fuel cells useful?
- Source of drinking water
- For instance, on a space- craft.
What is the issue with hydorgen being used in fuel cells?
What about in rechargable batteries.. what’s the advantage of not having hydrogen?
- Hydrogen is explosive - very difficult to store safely.
- Rechargable: no dangerous fuels, HOWEVER, some rechargable batteries can catch fire if not manufactured right!
What is the potential difference that fuel cells produce like in comparison to the P.D that rechargable batteries produce?
- Hydrogen fuel cells have low P.D so several are needed together.
- Rechargable batteries can produce greater P.D than hydrogen fuel cell.
