Fuel cells

Fuel cells convert the chemical energy in a fuel and oxygen into:

electricity

which direction do the electrons flow in a hydrogen-oxygen fuel cell?

from the anode to the cathode

what is an electrolyte?

a solution through which ions can flow

what are the electrodes in hydrogen- oxygen fuel cells made from?

porous carbon which has lots of tiny holes and a catalyst to speed up the reaction

what are the main advantages of hydrogen-oxygen fuel cells?

- hydrogen and oxygen are both renewable

- the reaction doesn’t produce any pollutants after disposal

- fuel cells last longer than batteries

what are the main disadvantages of hydrogen-oxygen fuel cells?

- hydrogen is highly explosive and flammable, so a danger to store

- hydrogen is a gas so it requires a large space to store

- hydrogen requires energy to be made (using fossil fuels) which are non renewable energy resources

- expensive to make due to high cost of catalysts

how does a hydrogen fuel cell work?

1. hydrogen comes in from the left inlet into the anode and is oxidised (loses electrons) to become hydrogen ions and this sets up a potential difference across the cell

2. the electrons pass along the wire to the cathode, then the hydrogen ions move through the electrolyte to the cathode

3. then the electrons and hydrogen ions react with oxygen to make water so oxygen is reduced ( gains electrons)

4. water then leaves the fuel cell by the outlet and the process is complete

what is the half equation at the anode?

H_{2 ——> 2H⁺ + 2e^-}

what is the half equation at the cathode?

O₂ + 4H⁺ +4e^- ——> 2H₂O

what is the overall equation for a hydrogen-oxygen fuel cell?

O₂ + 2H₂ ——> 2H₂O