The cell reaction of the cell fuel cell used in the space program is

Options

A. `C(s)+O_(2)(g) rarr CO_(2)(g)`
B. `CH_(4)(g)+O_(2)(g) rarr CO_(2)+H_(2)(l)`
C. `2H_(2)(g)+O_(2)(g) rarr 2H_(2)O(l)`
D. `2H_(2)O(l) rarr 2H_(2)(g)+O_(2)(g)`

Answer

C

Explanation

The hydrogen-oxygen fuel cell, which has many applications, is used in spacecraft to supplement the energy obtained from solar cells.
Liquid `H_(2)` is carried on board a s a propellant. The bolied-off `H_(2)` vapor that ordinarily would be lost is used in a fuel cell to generate electrical power.
Hydrogen (the fuel is supplied to the anode compartment. Oxygen (the oxidizer) is fed into the cathode compartment. The diffusion rates of the gases into the cell are carefully regulated for maximum efficiency. Oxygen is reduced at the cathode, which consists of porous carbon impregnated with a finely divided `Pt` o `Pd` catalyst.
Cathode
`O_(2)(g)+2H_(2)O(l)+4e^(-)overset("Catalyzing") rarr 4OH^(-)(aq.)`
The `OH^(-)` ions migrate through the electrolyte (an aqueous solution of a base) to the anode. The anode is also porous cabon containing a small amount of catalyst (`Pt, Ag`, or `CoO`). Here `H_(2)` is oxidized to `H_(2)O`.
Anode
`H_(2)(g)+2OH^(-)(aq.) rarr 2H_(2)O(l)+2e^(-)`
The net reaction obtained from the two half-reactions is `2H_(2)(g)+O_(2)(g) rarr 2H_(2)O(l)`
The pure water produced by the cell is drunk by the astronauts.