5.5.2.2 Fuel Cells

Question 1

How are fuel cells supplied?

Answer 1

• by an external source of fuel (e.g. hydrogen)
• and oxygen or air

Question 2

How does the fuel cell produce a potential difference?

Answer 2

• fuel is oxidised electrochemically within the fuel cell

Question 3

What does the overall reaction in a hydrogen fuel cell involve?

Answer 3

• oxidation of hydrogen to produce water

Question 4

What are the positives of using hydrogen fuel cells?

Answer 4

• can be used constantly
• only produces water when burnt

Question 5

What are the negatives of using hydrogen fuel cells?

Answer 5

• can only be used constantly provided fuel keeps being put in
• hydrogen is a gas and needs to be stored at high pressures so it is harder to transport

Question 6

What are the positives of using rechargeable cells and batteries?

Answer 6

• can be recharged by reversing reactions so fuel doesn’t need to keep being supplied

Question 7

What are the negatives of using rechargeable cells and batteries?

Answer 7

• hard to dispose of (non-biodegradable)
• will eventually stop working

Question 8

What is the half equation at the anode?

Answer 8

• H2(g) → 2e– +2H+(aq)

Question 9

What is the half equation at the cathode?

Answer 9

• 4H+(aq) + O2(g) + 4e → 2H2O(g)