All flashcards
Flashcard 1: What is the primary purpose of a hydrogen fuel cell?
Answer: To convert chemical energy into electrical energy. Converts hydrogen's chemical bonds into usable electricity through electrochemical reactions.
Flashcard 2: Which sector benefits from using hydrogen fuel cells for cleaner energy?
Answer: The transportation sector benefits. Vehicles can achieve zero local emissions using hydrogen power.
Flashcard 3: State the main advantage of hydrogen fuel cells over fossil fuels.
Answer: They produce no harmful emissions. Only water vapor is emitted, unlike fossil fuels that release greenhouse gases.
Flashcard 4: Which component of the fuel cell lets protons pass but not electrons?
Answer: The proton exchange membrane (PEM). Selective permeability allows ionic conduction while blocking electrons.
Flashcard 5: Identify a key limitation of hydrogen production via electrolysis.
Answer: It is energy-intensive and costly. Requires significant electrical input, making it expensive to operate.
Flashcard 6: Which gas is released as a waste product in traditional combustion engines?
Answer: Carbon dioxide (CO2) is released. Burning fossil fuels produces CO2 as a major greenhouse gas emission.
Flashcard 7: Which part of the hydrogen fuel cell separates hydrogen and oxygen?
Answer: The proton exchange membrane (PEM). Selectively allows protons to pass while blocking electrons and gases.
Flashcard 8: What type of fuel cell is most common in vehicles?
Answer: Proton exchange membrane fuel cell (PEMFC). Low operating temperature and compact design suit automotive applications.
Flashcard 9: Identify a disadvantage of using platinum in fuel cells.
Answer: Platinum is expensive and scarce. High cost and limited supply make platinum catalysts expensive.
Flashcard 10: What is a common method of producing hydrogen for fuel cells?
Answer: Electrolysis of water is common. Electric current splits water molecules into hydrogen and oxygen gases.
Flashcard 11: What is the role of the bipolar plates in a fuel cell?
Answer: They conduct electrons and distribute gases. Manage electrical current flow and distribute reactant gases evenly.
Flashcard 12: Which two elements are essential in a hydrogen fuel cell?
Answer: Hydrogen and oxygen are essential. Hydrogen provides protons and electrons, oxygen accepts them to form water.
Flashcard 13: What is a benefit of hydrogen fuel cells in space applications?
Answer: They provide water as a byproduct. Astronauts can drink the water produced as a valuable resource.
Flashcard 14: Identify the environmental benefit of using hydrogen fuel cells.
Answer: They reduce greenhouse gas emissions. Water vapor emission instead of CO2 helps combat climate change.
Flashcard 15: Identify the main component used as a fuel in hydrogen fuel cells.
Answer: Hydrogen gas is the main fuel component. Hydrogen gas provides the protons and electrons needed for the reaction.
Flashcard 16: What is the main challenge in using hydrogen fuel cells?
Answer: The storage and transportation of hydrogen. Hydrogen is highly flammable and requires specialized containment systems.
Flashcard 17: What is the energy density of hydrogen compared to gasoline?
Answer: Hydrogen has a higher energy density by weight. Hydrogen contains more energy per kilogram than gasoline.
Flashcard 18: What is the byproduct of a hydrogen fuel cell?
Answer: Water is the byproduct. The only emission from the electrochemical reaction between hydrogen and oxygen.
Flashcard 19: In a hydrogen fuel cell, what carries electrons from anode to cathode?
Answer: An external circuit carries the electrons. Electrons flow through the external circuit to complete the electrical loop.
Flashcard 20: What kind of energy transformation occurs in a hydrogen fuel cell?
Answer: Chemical energy to electrical energy. Direct conversion without thermal combustion intermediates.
Flashcard 21: What is the typical operating temperature for PEM fuel cells?
Answer: Around 80°C (176°F). Optimal temperature for efficient proton conduction in the membrane.
Flashcard 22: What is the typical voltage output of a single hydrogen fuel cell?
Answer: Approximately 0.7 volts per cell. Standard output for proton exchange membrane fuel cells under normal conditions.
Flashcard 23: What is the cathode reaction in a hydrogen fuel cell?
Answer: O2+4H++4e−→2H2O. Oxygen gains electrons and protons at the cathode to form water.
Flashcard 24: What is the anode reaction in a hydrogen fuel cell?
Answer: 2H2→4H++4e−. Hydrogen molecules lose electrons at the anode, becoming protons.
Flashcard 25: Identify one application of hydrogen fuel cells.
Answer: They are used in transportation, such as fuel cell vehicles. Cars, buses, and trucks can run on hydrogen fuel cells for zero emissions.
Flashcard 26: Which gas is released as a waste product in traditional combustion engines?
Answer: Carbon dioxide (CO2) is released. Burning fossil fuels produces CO2 as a major greenhouse gas emission.
Flashcard 27: What is the chemical reaction formula in a hydrogen fuel cell?
Answer: 2H2+O2→2H2O+electricity. Shows hydrogen and oxygen combining to produce water and electrical energy.
Flashcard 28: What is the main component of the exhaust from a hydrogen fuel cell?
Answer: Water vapor is the main component. Clean water vapor is the only emission from hydrogen fuel cells.
Flashcard 29: What is the role of the catalyst in a hydrogen fuel cell?
Answer: It speeds up the chemical reaction. Lowers activation energy needed for hydrogen oxidation and oxygen reduction.
Flashcard 30: What is the efficiency range of hydrogen fuel cells?
Answer: Typically 40% to 60% efficient. Higher than internal combustion engines due to direct energy conversion.