Question 1: Define a hydrogen fuel cell and explain how it generates electricity.

Answer: A hydrogen fuel cell is a device that converts chemical energy from hydrogen and oxygen into electrical energy through electrochemical reactions, producing water as a by-product.

Question 2: Describe the role of the anode and cathode in a hydrogen fuel cell.

Answer: The anode is where hydrogen molecules are split into protons and electrons; the cathode is where oxygen combines with electrons and protons to form water.

Question 3: Explain why water is produced in a hydrogen fuel cell.

Answer: Water is produced when protons, electrons, and oxygen combine during the electrochemical reaction at the cathode.

Question 1: Calculate the amount of electricity (in coulombs) produced when 2 moles of hydrogen gas are reacted in a hydrogen fuel cell. (Use Faraday's constant: 96,500 C/mol).

Answer: 193000 C

Question 2: If a hydrogen fuel cell produces a current of 3 amperes over 2 hours, how much charge has passed through the circuit? (Recall 1 hour = 3600 seconds).

Answer: 216000 C

Question 1: List three safety precautions that should be taken when handling hydrogen gas in a laboratory or industrial setting.

Answer: Ensure proper ventilation to prevent accumulation, avoid sparks or open flames, and use appropriate protective equipment like gloves and goggles.

Question 2: Describe a basic experiment to test the efficiency of a hydrogen fuel cell.

Answer: Set up the fuel cell with a known volume of hydrogen and oxygen, connect an external circuit with a voltmeter and a resistor, measure voltage and current output, and calculate the electrical energy produced over time to determine efficiency.

Question 1: A hydrogen fuel cell produces a voltage of 0.7 V and a current of 2.5 A for 30 minutes. Calculate the total electrical energy generated in joules.

Answer: 3150 J

Question 2: If the fuel cell's maximum power output is 1.75 W, estimate how long it can operate continuously while producing 350 J of energy.

Answer: Approx. 200 seconds

Question 1: Explain the electrochemical process occurring at the anode and cathode in a hydrogen fuel cell. Include the chemical equations involved. (6 marks)

Answer: At the anode, hydrogen molecules are split into protons and electrons: 2H₂ → 4H⁺ + 4e⁻. The electrons flow through the external circuit, providing electrical energy. At the cathode, oxygen molecules react with electrons and protons to produce water: O₂ + 4H⁺ + 4e⁻ → 2H₂O. This process generates electricity and water as the only by-product.

Question 1: Describe one advantage and one disadvantage of using hydrogen fuel cells in cars.

Answer: Advantage: Zero emissions, as they only produce water. Disadvantage: Hydrogen storage and production can be challenging and costly.

Question 2: Suggest a reason why hydrogen fuel cells are considered a sustainable energy source.

Answer: Hydrogen can be produced from renewable sources like water using electrolysis, making it a sustainable and clean energy option.