Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryElectrochemistry2 Marks
Question
What are ‘fuel Cells’? Write cathode and anode reaction in a fuel cell.
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Answer
fuel cells:
The galvanic cell in which two energy of combustion of fuels is directly connected into electrical energy Called fuel cell. Reaction of cell : Oxidation at anode :
At anode hydrogen gas is oxidized to $H_2O.$
$2 H _2( g )+4 OH ^{-}( aq ) \longrightarrow 4 H _2 O ( l )+4 e ^{-}$ Reduction at cathode $(+)$
The electrons released at anode travel to cathode through the external circuit.
Here $O_2(g)$ is reduced to $OH -$
$O _2( g )+2 H _2 O ( l )+4 e ^{-} \longrightarrow 4 OH ^{-}$ Cell reactions in a fuel cell:
Oxidation at the anode $(-):$
Oxidation of hydrogen gas to water occurs at the anode.
$2H_{2(g)} + 4OH^-_{(aq)} \rightarrow 4H_2O_{(l)} + 4e^-$
Reduction at the cathode $(+):$
Reduction of oxygen gas to $OH$ ions occurs at the cathode.
$O_{2(g)} + 2H_2O_{(l)} + 4e^- \rightarrow 4OH^-_{(aq)}$
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