Question

The electrode reaction that takes place at the anode of ${{C}}{{{H}}_4}{{ - }}{{{O}}_2}$ fuel cell is:
A. $2{{{O}}_2} + 8{{{H}}^ + } + 8{{{e}}^ - } \to 4{{{H}}_2}{{O}}$
B. ${{C}}{{{H}}_4} + 2{{{H}}_2}{{O}} \to {{C}}{{{O}}_2} + 8{{{H}}^ + } + 8{{{e}}^ - }$
C. \[{{C}}{{{H}}_4} + {{{O}}_2} \to {{C}}{{{O}}_2} + 2{{{H}}_2}{{O}}\]
D. $2{{{H}}^ + } + 2{{{e}}^ - } \to {{{H}}_2}$

Answer 1

Hint:Before finding the reaction which takes place in the fuel cell, we shall know about the fuel cell first. Fuel cells are a type of electrochemical cell. It consists of two electrodes. The electrolyte in these cells convert the chemical energy to electrical energy. This conversion takes place between fuel and oxidant.

Complete step by step answer:
The fuel cells consist of majorly cathode, anode, electrolyte and catalyst. Generally, a fuel cell creates electricity through an electrochemical process by using hydrogen and oxygen. Hydrogen-rich fuel can also be used instead of hydrogen.
Fuel cells are classified on the basis of the type of electrolyte and types of fuel and oxidant. Based on the type of fuel and oxidant, fuel cells are classified into hydrogen-oxygen fuel cell, hydrogen rich gas-air fuel cell, ammonia-air, synthesis gas-air, hydrocarbon-air fuel cells.
${{C}}{{{H}}_4}{{ - }}{{{O}}_2}$ fuel cell is a type of hydrocarbon-air fuel cells. In this type of fuel cells, methane is used as fuel and oxygen is used as oxidant.
The total reaction which undergoes in this type of fuel cells is:
\[{{C}}{{{H}}_4} + 2{{{O}}_2} \to {{C}}{{{O}}_2} + 2{{{H}}_2}{{O}}\]
At cathode, oxygen is reduced while at anode, methane is oxidized. The reactions at cathode and anode are given below:
At cathode: \[2{{{H}}_2}{{O}} \to {{{O}}_2}{{ }} + {{ }}4{{{H}}^ + }{{ }} + {{ }}4{{{e}}^{ - {{ }}}}\]
At anode: ${{C}}{{{H}}_4} + 2{{{H}}_2}{{O}} \to {{C}}{{{O}}_2} + 8{{{H}}^ + } + 8{{{e}}^ - }$
Overall reaction: \[{{C}}{{{H}}_4} + {{{O}}_2} \to {{C}}{{{O}}_2} + 2{{{H}}_2}{{O}}\]
Thus the reaction taking place at anode is ${{C}}{{{H}}_4} + 2{{{H}}_2}{{O}} \to {{C}}{{{O}}_2} + 8{{{H}}^ + } + 8{{{e}}^ - }$

Hence, the correct option is B.

Note:
The electrons are moved from anode to cathode through an electric circuit. This produces an electric current. The fuel cell produces power which depends upon the type of fuel cell, size of the fuel cell, temperature and pressure. All of the fuel cells have different types of advantages and disadvantages.