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IB Chemistry SL 1.3.5 Fuel Cells Questions

Use real exam questions to compare fuel cells with batteries, write hydrogen–oxygen electrode equations and interpret breathalyser measurements.

Syllabus
First assessment 2025
Course
Chemistry SL
Level
SL

Exam points

  • Compare fuel cells with rechargeable batteries using reaction reversibility, continuity of operation and the need for continuously supplied reactants.
  • Write or identify balanced anode, cathode and overall half-equations for a hydrogen–oxygen fuel cell in the stated alkaline or acidic electrolyte, including correct species and states.
  • Explain how a fuel-cell current or potential can determine ethanol concentration and discuss a supported practical or environmental disadvantage of hydrogen or fuel-cell use.

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Study 1.3.5—Fuel cells conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Chemistry SL 1.3.5 Fuel Cells Questions question 1

[Maximum number: 1]

The methanol fuel cell relies on the oxidation of methanol by oxygen. The two half-equations are as follows:

Anode: CH3OH(l)+H2O(l)→CO2( g)+6H+(aq)+6e−\mathrm{CH}_{3} \mathrm{OH}(\mathrm{l})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+6 \mathrm{H}^{+}(\mathrm{aq})+6 \mathrm{e}^{-}

Cathode: 4H+(aq)+O2( g)+4e−→2H2O(l)4 \mathrm{H}^{+}(\mathrm{aq})+\mathrm{O}_{2}(\mathrm{~g})+4 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})

What is the balanced equation for the overall reaction?

Figure for Question IB Chemistry SL 1.3.5 Fuel Cells Questions question 1 — IB Chemistry SL
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