With reference to ‘fuel cells’ in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements:

1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products.
2. Fuel cells can be used for powering buildings and not for small devices like laptop computers.
3. Fuel cells produce electricity in the form of Alternating Current (AC).

Which of the statements given above is/are correct?

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

Explanation

Only statement 1 is correct

• A fuel cell is a device that converts chemical energy into electrical energy. It uses hydrogen and oxygen gas as fuel to generate electricity. However, there is no combustion involved.
• Fuel cells can vary from tiny devices producing only a few watts of electricity, right up to large power plants producing megawatts.
• Fuel Cell working mechanism:
  • A fuel cell consists of a cathode, an anode, and an electrolyte.
  • The electrolyte enables the movement of the ions between the electrodes.
  • At the anode, catalyst causes the fuel to undergo oxidation & generates +ve charged ions & electrons.
  • The ions move from the anode to the cathode and the same time, the electrons flow from the anode to the cathode through an external circuit, producing direct current electricity.
  • At the cathode, another catalyst causes ions, electrons, & oxygen to react, forming water as by-product.
  • The reaction rate of this electrochemical reaction is quite low.
  • Catalysts such as platinum or palladium or gold are used to speed up the reaction.

Answer: (a) 1 only; Difficulty Level: Hard