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Electrochemistry

Question
CBSEENCH12006092
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What are fuel cells? Write the electrode reactions of a fuel cell which uses the reaction of hydrogen with oxygen.

Solution
A device to convert chemical energy of fuel into electrical energy is called fuel cell.


Hydrogen-oxygen fuel cell: The cell consists of three compartments separated from one another by porous electrode. The hydrogen gas is fed into one compartment and the oxygen gas is fed into another compartment. These gases then diffuse slowly through the electrodes and react with an electrolyte that is in the central compartment. The electrodes are made of a conducting material, such as graphite, with a sprinkling of platinum to act as a catalyst, and the electrolyte is an aqueous solution of a base. The reactions are
Cathode: O2(g) + 2H2O(l) + 4e–-----> 4OH–(aq)
Anode: 2H2 (g) + 4OH–(aq)-----> 4H2O(l) + 4e–
Overall reaction being:

2H2(g) + O2(g) ----->2H2O(l )
Advantages: (i) Fuel cells are efficient and free from pollution.
(ii) The only product in the reaction of fuel cell is water which can be removed and the astronauts of a spacecraft can drink it.

Some More Questions From Electrochemistry Chapter

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The molar conductivity of 0.025 mol L–1 methanoic acid is 46.1 S cm2 mol–1. Calculate its degree of dissociation and dissociation constant. Give λ°(H+) = 349.6 S cm2 mol–1 and λ° (HCOO– ) = 54.6 s cm2 mol–1.

If the current of 0.5 ampere flows through a metallic wire for 2 hours, then how many electrons flow through the wire?

Suggest a list of metals that are extracted electrolytically.

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What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr2O72-?

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