Cells

• What do cells contain?

  chemicals which react to produce electricity
• electro-chemical cell

  a basic system made up of two different electrodes in contact with an electrolyte
• What is the voltage of a cell dependent upon?

  • type of electrodes
  • type of electrolyte
• How will the type of electrolyte affect the voltage?

  different ions in the solution will react differently with the metal electrodes used
• What happens to the voltage if the difference in reactivity of electrodes increases?

  the bigger the size of the voltage
• What do batteries consist of?

  two or more cells connected together in series to provide a greater voltage.
• Non-Rechargeable Batteries

  • irreversible reactions take place at the electrodes
  • once reactant is used up - the reaction can no longer happen
  • no electricity/electric charge is produced
  • products are unable to be turned back into reactants
• Rechargeable Batteries

  chemical reactions are reversed when an external electrical current is supplied
• What is an example of a Non-Rechargeable Battery?

  alkaline batteries
• What are fuel cells?

  an electrical cell that's supplied by an external source of fuel and oxygen or air - uses energy from reaction - to produce electrical energy efficiently
• What happens when the fuel enters the cell?

  the fuel is oxidised electrochemically within the fuel cell to produce a potential difference
• What does he overall reaction in a hydrogen fuel cell involve?

  the oxidation of hydrogen to produce water + energy