Home
Class 12
CHEMISTRY
Fuel cells : Fuel cells are galvanic cel...

Fuel cells `:` Fuel cells are galvanic cells in which the chemical energy of fuel cell is directly converted into electrical energy. A type of fuel cell is a hydrogen `-` oxygen fuel cell. It consists of two electrodes made up of two porous graphite impregnated with a catalyst `(` platinum, silver, or metal oxide `).` The electrodes are placed in aqueous solution of `NaOH` . Oxygen and hydrogen are continuously fed into the cell. Hydrogen gets oxidized to `H^(o+)` which is neutralized by `overset(c-)(O)H, i.e.,` anodic reaction.

At cathode, `O_(2)` gets reduced to `overset(c-)(O)H`

Hence, the net reaction is
The overall reaction has
`DeltaH=-285.6 kJ mol^(-1)` and `DeltaG=-237.4 kJ mol^(-1)` at `25^(@)C`
If the cell voltage is `1.23V` for the `H_(2)-O_(2)` fuel cell and for the half cell `:`

A

`9.5 %`

B

`89%`

C

`83 %`

D

`95%`

Text Solution

Verified by Experts

The correct Answer is:
C
Thermodynamic efficiency
`= (Delta G)/(Delta H) = (-n FE)/(Delta H)`
`= (-2 xx 96500 xx 1.23)/(-285.8 xx 10^(3))`
`= 0.83 or 83 %`
Promotional Banner

Topper's Solved these Questions

  • ELECTROCHEMISTRY

    MODERN PUBLICATION|Exercise COMPETITION FILE (OBJECTIVE TYPE QUESTIONS) MATRIX MATCH TYPE QUESTIONS|3 Videos

  • ELECTROCHEMISTRY

    MODERN PUBLICATION|Exercise COMPETITION FILE (OBJECTIVE TYPE QUESTIONS)Matching Type Questions|1 Videos

  • ELECTROCHEMISTRY

    MODERN PUBLICATION|Exercise COMPETITION FILE (OBJECTIVE TYPE QUESTIONS) C MULTIPLE CHOICE QUESTIONS|10 Videos

  • D AND F-BLOCK ELEMENTS

    MODERN PUBLICATION|Exercise UNIT PRACTICE TEST|12 Videos

  • GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

    MODERN PUBLICATION|Exercise COMPETION FILE (Integer Type Numerical Value Type Questions)|5 Videos

Similar Questions

Explore conceptually related problems

Fuel cells : Fuel cells are galvanic cells in which the chemical energy of fuel cell is directly converted into electrical energy. A type of fuel cell is a hydrogen - oxygen fuel cell. It consists of two electrodes made up of two porous graphite impregnated with a catalyst ( platinum, silver, or metal oxide ). The electrodes are placed in aqueous solution of NaOH . Oxygen and hydrogen are continuously fed into the cell. Hydrogen gets oxidized to H^(o+) which is neutralized by overset(c-)(O)H, i.e., anodic reaction. At cathode, O_(2) gets reduced to overset(c-)(O)H Hence, the net reaction is The overall reaction has DeltaH=-285.6 kJ mol^(-1) and DeltaG=-237.4 kJ mol^(-1) at 25^(@)C What is the value of DeltaS^(c-) for the fuel cell at 25^(@)C ?

Fuel cells : Fuel cells are galvanic cells in which the chemical energy of fuel cell is directly converted into electrical energy. A type of fuel cell is a hydrogen - oxygen fuel cell. It consists of two electrodes made up of two porous graphite impregnated with a catalyst ( platinum, silver, or metal oxide ). The electrodes are placed in aqueous solution of NaOH . Oxygen and hydrogen are continuously fed into the cell. Hydrogen gets oxidized to H^(o+) which is neutralized by overset(c-)(O)H, i.e., anodic reaction. At cathode, O_(2) gets reduced to overset(c-)(O)H Hence, the net reaction is The overall reaction has DeltaH=-285.6 kJ mol^(-1) and DeltaG=-237.4 kJ mol^(-1) at 25^(@)C Suppose the concentration of hydroxide ioin in the cell is doubled, then the cell voltage will be

Fuel cells : Fuel cells are galvanic cells in which the chemical energy of fuel cell is directly converted into electrical energy. A type of fuel cell is a hydrogen - oxygen fuel cell. It consists of two electrodes made up of two porous graphite impregnated with a catalyst ( platinum, silver, or metal oxide ). The electrodes are placed in aqueous solution of NaOH . Oxygen and hydrogen are continuously fed into the cell. Hydrogen gets oxidized to H^(o+) which is neutralized by overset(c-)(O)H, i.e., anodic reaction. At cathode, O_(2) gets reduced to overset(c-)(O)H Hence, the net reaction is The overall reaction has DeltaH=-285.6 kJ mol^(-1) and DeltaG=-237.4 kJ mol^(-1) at 25^(@)C A fuel cell is I. A voltaic cell in which continuous supply of fuels are sent at anode to perform oxidation. II. A voltaci cell in which fuels such as :CH_(4),H_(2), and CO are used up at anode. III. One which involves the reaction of H_(2)-O_(2) fuel cell such as : Anode :2H_(2)O+4overset(c-)(O)H rarr 4H_(2)O(l)+4e^(c-) Cathode : O_(2)+2H_(2)O(l) =4e^(-) rarr 4overset(c-)(O)H IV. The efficiency of H_(2)-O_(20 fuel cell is 70 to 75%

The overall reactions of a hydrogen -oxygen fuel cell is