Cells
When 2 different metals are placed in an electrolyte then we can produce electricity. (An electrolyte is a solution that can conduct electricity). This is because they create a potential difference between them. And they react with the electrolyte and the spare electrons from the reaction flow from high to low potential (A bit like in electrolysis)
- A cell can only produce electricity for a certain period of time before the chemicals in the cell run out and the reaction stops.
- They only produce electricity is we use metals with different reactivities - the size of potential difference depends on the difference in reactivity
- The electrolyte also effects potential difference
Battery
A battery is two or more cells connected in series to produce a grater voltage
Rechargeable Cells and Batteries
- Alkaline batteries are none rechargeable as the reactants eventually run out. The reaction can’t be reversed so they are non rechargeable
- Rechargeable batteries can be recharged as the chemical reaction can be reversed when an electrical current is supplied
Hydrogen Fuel Cells
- A fuel (hydrogen) is reacted with oxygen, this chemical reaction produces an electric current.
- The only waste product is water
- Hydrogen is being oxidised
- Overall equation
Half Equations
At the negative electrode:
Advantages
- Produce electricity as long as hydrogen is provided
- Do not get less efficient over time
- Can be a source of drink water
Disadvantages
- Hydrogen is explosive and difficult to store
- Low potential difference