Lesson 5: Fuel cells Flashcards

1
Q

What are fuel cells?

A
  • Fuel cells include a reaction between H2 and O2 to produce an electric current.
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2
Q

What happens to the electrons that the Hydrogen molecules split into?

A
  • Electrons pass through the wire and generate the electric current.
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3
Q

What is the half- equation for hydrogen at the negative electrode?

A

2H₂ —> 4H⁺ +4e⁻

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4
Q

What is the half equation at the positive electrode?

A

O₂ + 4H⁺ + 4e⁻ –> 2H₂O

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5
Q

What is the overall reaction in a fuel cell?

A

2H₂ + O₂ –> 2H₂O
Hydrogen has been oxidised to produce water…

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6
Q

What is the effect of the fuel being oxidised?

A
  • Fuel oxidised electrochemically within the fuel cell to produce a potential difference.
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7
Q

How long will hydrogen cells produce electricity for?
How long will rechargable batteries produce electricity for?

A

1.) For as long as you provide hydrogen.
2.) Rechargable batteries run out and need to be recharged.

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8
Q

Do hydrogen cells get less efficient the more they run?
How about rechargable batteries?

A

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.

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9
Q

How is the H₂O produced from hydrogen fuel cells useful?

A
  • Source of drinking water
  • For instance, on a space- craft.
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10
Q

What is the issue with hydorgen being used in fuel cells?
What about in rechargable batteries.. what’s the advantage of not having hydrogen?

A
  • Hydrogen is explosive - very difficult to store safely.
  • Rechargable: no dangerous fuels, HOWEVER, some rechargable batteries can catch fire if not manufactured right!
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11
Q

What is the potential difference that fuel cells produce like in comparison to the P.D that rechargable batteries produce?

A
  • Hydrogen fuel cells have low P.D so several are needed together.
  • Rechargable batteries can produce greater P.D than hydrogen fuel cell.
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