Question

In ${H_2} - {O_2}$ fuel cell the reaction occurring at cathode is.
A. $2{H_2}\left( g \right) + {O_2}\left( g \right)\xrightarrow{{}}2{H_2}O\left( l \right)$.
B. ${O_2}\left( g \right) + 2{H_2}O\left( l \right) + 4{e^ - }\xrightarrow{{}}4O{H_{\left( {aq} \right)}}$.
C. ${H^ + } + {e^ - }\xrightarrow{{}}\dfrac{1}{2}{H_2}$.
D. )${H^ + }_{\left( {aq} \right)} + O{H^ - }_{\left( {aq} \right)}\xrightarrow{{}}{H_2}O\left( l \right)$.

Answer 1

Hint: We know that a device that converts chemical potential energy into electrical energy is called a fuel cell. Water, electricity, and heat are the products of this cell.

Complete step by step answer: Now, we see fuel cells in detail.
Fuel cells:
A hydrogen-oxygen fuel cell contains an electrolyte solution like potassium hydroxide solution and two inert carbon electrodes. The gases of hydrogen and oxygen are bubbled through the anode and cathode compartments in which the following reactions take place.
The half cell and net reaction:
At anode:$2{H_2}\left( g \right) + 4O{H^ - }\xrightarrow{{}}4{H_2}O\left( l \right) + 4{e^ - }$
At cathode:${O_2}\left( g \right) + 2{H_2}O\left( l \right) + 4{e^ - }\xrightarrow{{}}4O{H^ - }$
Net reaction: $2{H_2}\left( g \right) + {O_2}\left( g \right)\xrightarrow{{}}2{H_2}O\left( l \right)$
We must remember that the standard emf of the hydrogen-oxygen cell is\[1.23V\], the positive value of the emf value indicates that the cell reaction is spontaneous under standard conditions. The porous carbon electrodes in the cell serve as electrical conductors and also provide the necessary surfaces for the initial decomposition of the molecules into atomic species.
Therefore, option B is correct.

Note: Let us discuss applications of fuel cells.
-Fuel cell technology has a lot of applications. A few applications of fuel cells are listed below.
-Fuel cells are more eco-friendly than internal combustion engine-based vehicles so they are used in fuel electric vehicles.
-Fuel cells are used to power many space expeditions including the Apollo space program.
-Usually, the by-products produced from these cells are heat and water.
-These electrochemical cells are also used to control several electronic devices.
-They are also used as primary or backup sources of electricity in many isolated areas.