Question

Name the cell which was used in the Apollo space programme for providing electrical power.

Hint:

The Hydrogen-Oxygen Fuel Cell is a very important board examination question. Remember: \[ 2H_2 + O_2 \rightarrow 2H_2O \] Electrical energy is produced directly from this reaction. Apollo spacecraft used Hydrogen-Oxygen Fuel Cells for electrical power generation.

Answer 1

Concept: A fuel cell is an electrochemical cell that converts the chemical energy of a fuel directly into electrical energy through redox reactions. Unlike ordinary batteries, fuel cells can continue to produce electricity as long as the reactants are continuously supplied. Fuel cells are highly efficient, environmentally friendly, and capable of producing electricity for long durations. Because of these advantages, they are widely used in spacecraft, submarines, and modern clean-energy technologies.

Step 1: Understanding the fuel cell used in the Apollo space programme. The Apollo space missions required a reliable source of electrical energy for operating various onboard instruments, communication systems, navigation equipment, and life-support systems. For this purpose, scientists used the \[ \boxed{\text{Hydrogen-Oxygen Fuel Cell}} \] which generates electrical energy through the reaction of hydrogen and oxygen.

Step 2: Working principle of the Hydrogen-Oxygen Fuel Cell. In this fuel cell:

• Hydrogen gas is supplied continuously at the anode.

• Oxygen gas is supplied continuously at the cathode.

• An electrolyte facilitates the movement of ions.

• Chemical energy is directly converted into electrical energy.
The overall reaction occurring in the fuel cell is \[ 2H_2(g)+O_2(g)\rightarrow 2H_2O(l) \] During this reaction, electrons are released and flow through the external circuit, producing electricity.

Step 3: Advantages of using Hydrogen-Oxygen Fuel Cells in spacecraft. The Hydrogen-Oxygen Fuel Cell was preferred in the Apollo missions because:

• It has high efficiency.

• It provides a continuous supply of electrical energy.

• It is lightweight compared to conventional batteries.

• The only by-product formed is water.

• The water produced could also be utilized by astronauts for various purposes.
Thus, the fuel cell served a dual purpose of generating electricity and producing water during the mission.

Step 4: Identifying the required answer. Since the Apollo space programme used hydrogen and oxygen as reactants to generate electrical power, the cell employed was the \[ \boxed{\text{Hydrogen-Oxygen Fuel Cell}} \]

Final Answer: \[ \boxed{\text{Hydrogen-Oxygen Fuel Cell}} \]