fuel cells

• what does a fuel cell diagram look like

  this

  
• what are fuel cells

  where we react a fuel eg hydrogen with either pure oxygen or air, inside a chemical reaction takes place, producing an electric current
• whats the waste product for a hydrogen fuel cell

  water
• what is the half equation at the negative electrode

  $2H.2-> 4H^+$$+$$4e^-$
• the electric current comes from...


  the electrons lost at the negative electrode from hydrogen
• what happens at the positive electrode

  oxygen molecules combine with the electrons and the hydrogen ions (from the neg electrode)

  $O.2 +$$4H^+$$+$$4e^- -> 2H.2O$
• in terms of oxidation what happens in a hydrogen fuel cell

  hydrogen becomes oxidised as it combines with oxygen and loses electrons
• overall equation?

  $2H.2 +$$O.2 -> 2H.20$
• advantages of hydrogen fuel cells

  produce electricity as long as hydrogen is provided

  they do not get less efficient the longer they run

  can also be a source of drinkable water
• disadvantages of hydrogen fuel cells

  run on hydrogen which is explosive gas and difficult to store safely

  produce a relatively low pd/voltage so several are needed together