Fuel Cells

• What is a fuel cell?

  An electrical cell supplied with fuel and oxygen, that uses energy from the reaction to produce electricity.
• How do hydrogen-oxygen fuel cells work?

  1. The electrolyte is usually an acid and the electrodes are often porous carbon with a catalyst
  2. Hydrogen goes in the negative anode and oxygen in the positive cathode (opposite to electrolysis)
  3. Hydrogen loses electrons and forms H+ ions (oxidation) and these ions move to the cathode
  4. Oxygen gains electrons at the cathode and then reacts with H+ ions to make water (reduction)
  5. The overall reaction is hydrogen plus oxygen makes water
• What are the 3 advantages of using fuel cells in cars?

  1. Doesn’t produce as many pollutants
  2. Rechargeable (though there is a limit to how many times they can recharge)
  3. Fuel cells store more energy than batteries
• What are the 3 disadvantages of using fuel cells in cars?

  1. Hydrogen takes up lots of space as it is a gas
  2. Hydrogen is explosive when mixed with water so hard to store safely
  3. Making hydrogen requires electricity (which is usually generated through burning fossil fuels)
• What is the reaction at the cathode (positive electrode) in a hydrogen- oxygen fuel cell?

  4H⁺ + O₂ + 4e⁻ —> 2H₂O
• What is the reaction at the anode (negative electrode) in the hydrogen-oxygen fuel cell?

  H₂ —> 2e⁻ + 2H⁺
• What is a commonly used electrolyte in hydrogen-oxygen fuel cells?

  Phosphoric acid
• What is the overall reaction in a hydrogen-oxygen fuel cell?

  2H₂ + O₂ —> 2H₂O
• What are the electrodes in fuel cells made from?

  Porous carbon