fuel cells Flashcards
fuel cell
an electrical cell that’s supplied with a fuel and oxygen and uses energy from the reaction to produce electrical energy efficiently
what happens when a fuel enters a cell?
it becomes oxidised and sets up a potential difference
give an example of a fuel cell
hyrdogen-oxygen
by-products
water and heat
why are fuel cells good for the environment compared to other fuel?
they don’t produce as many pollutants
why are fuel cells better than batteries in electric vehicles?
- electric vehicles have batteries which are more polluting to dispose of-made from highly toxic metal compounds
- batteries can only be recharged so many time
- batteries are more expensive
- batteries store less energy so need to be recharged more often
what type of reaction is in an hydrogen-oxygen fuel cell?
redox
what is different about the electrodes compared to electrolysis?
they are switched-anode is negative
where do hydrogen and oxygen go?
hydrogen-anode compartment
oxygen-cathode compartment
what happens at the anode?
hydrogen loses electrons to produce H⁺ ions (oxidation)
half equation at anode
H₂ -> 2H⁺ + 2e⁻
where do H⁺ ions move to?
the cathode
what happens at the cathode?
oxygen gains electrons from the cathode and reacts with H⁺ ions (from the acidic electrode) to make water (reduction)
half equation at cathode
O₂ + 4H⁺ + 4e⁻ -> 2H₂O
what is the electric current?
the electrons flow through an external circuit from the anode to the cathode
