Energy Changes: Chemical Cells and Fuel Cells Flashcards
What is a cell?
A cell is composed of two electrodes dipped in an electrolyte solution. It produces electricity from a chemical reaction.
What is a battery?
A battery consists of two or more cells connected in series.
What determines the voltage obtained from a cell?
- the metals used as electrodes
- the concentration of the electrolyte
- temperature of electrolyte
- type of electrolyte
What are some advantages of using cells and batteries?
- convenient
- some are rechargeable
What are some disadvantages of using cells and batteries?
- contain harmful chemicals
Describe rechargeable and non-rechargeable cells.
Rechargeable - chemical reactions are reversed when an external current is supplied
Non-rechargeable - reactants (ions in electrolyte and metal ions on the electrodes) are used up, cannot be recharged
What is a fuel cell?
Fuel cells are supplied by fuel and oxygen to oxidise the fuel and to generate electricity?
What is the overall reaction in a hydrogen fuel cell?
2H2 + O2 → 2H2O
What is the half equation for the cathode in a hydrogen fuel cell?
2H2 → 4H+ +4e-
What is the half equation for the anode in a hydrogen fuel cell?
O2 + 4H+ + 4e- → 2H2O
What are the advantages of hydrogen fuel cells?
- no pollutants releases like CO2
- no recharging
What are the disadvantages of hydrogen fuel cells?
- H2 is flammable and a gas so difficult to store
- fossil fuels may have to be used to produce them
How does a simple cell work?
- The electrolyte contains ions which react with the electrodes.
- The chemical reaction between the electrolyte and the electrodes sets up a charge difference between the electrodes
- The electrodes are connected by a wire allowing the change to flow producing electricity.
How do you calculate the overall voltage of a battery?
the sum of the voltage of all the cells
What must the electrodes be made of in cells?
something that conducts electricity, this is usually metals
