Q4(b)(ii). Concentration cells; fuel cells as energy converters
Define concentration cell and mention its types. Justify the statement "Fuel cells are energy conversion devices and not energy storage devices."
Answer in brief
A concentration cell has the same electrode reaction on both sides and its EMF comes only from a difference in concentration (E°cell = 0); a fuel cell holds no stock of reactants and only converts their free energy into electricity.
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Coversconcentration cellfuel cellwith and without transferenceH₂–O₂ fuel cellEMF
All parts of Question 4
- 4(a) Triple point, stable phase and enthalpy of sublimation of a new drug15 marks
- 4(b)(i) Polarography and concentration polarisation15 marks
- 4(b)(ii) Concentration cells; fuel cells as energy converters5 marks
- 4(c)(i) Time of maximum concentration of B in A → B → C10 marks
- 4(c)(ii) Yield of P₁ from three parallel paths5 marks