Fuel cellsEdexcel International A Level Chemistry: Flashcards
What these 12 flashcards ask
- What is a fuel cell?
- Give the half-equation at the negative electrode of an acidic H₂–O₂ fuel cell.
- Give the half-equation at the positive electrode of an acidic H₂–O₂ fuel cell.
- Give the half-equation at the negative electrode of an alkaline H₂–O₂ fuel cell.
- Give the half-equation at the positive electrode of an alkaline H₂–O₂ fuel cell.
- What is the overall equation for the H₂–O₂ fuel cell?
- What is E°cell for the H₂–O₂ fuel cell?
- Why can a fuel cell run continuously?
- Name a hydrogen-rich fuel used instead of hydrogen.
- Give the anode half-equation for the acidic methanol fuel cell.
- Give the overall equation for the methanol fuel cell.
- Give one advantage and one disadvantage of a hydrogen fuel cell.
Exam questions on Fuel cells
- A hydrogen–oxygen fuel cell with an acidic electrolyte is used to power a small vehicle. Standard electrode potentials: 2H⁺(aq) + 2e⁻ ⇌ H₂(g) 0.00 V; O₂(g) + 4H⁺(aq) + 4e⁻ ⇌ 2H₂O(l) +1.23 V.Explain why the electrolyte, which allows H⁺ ions to pass from one electrode to the other, is needed in this fuel cell.2 marks
- A hydrogen–oxygen fuel cell uses aqueous potassium hydroxide as the electrolyte.Write the half-equation for the reaction at the negative electrode of this fuel cell and use oxidation numbers to show that it is an oxidation.2 marks
- A methanol fuel cell uses an acidic electrolyte. The half-equations are: anode CH₃OH(l) + H₂O(l) → CO₂(g) + 6H⁺(aq) + 6e⁻; cathode O₂(g) + 4H⁺(aq) + 4e⁻ → 2H₂O(l). Use F = 96 500 C mol⁻¹ and M(CH₃OH) = 32.0 g mol⁻¹.Combine the half-equations to deduce the overall equation for the reaction in the methanol fuel cell.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).