Chemical Cells (Oxford AQA IGCSE Chemistry)

Chemical Cells

• A chemical cell is a source of electrical energy

• The simplest design consists of two electrodes made from metals of different reactivity immersed in an electrolyte and connected to an external voltmeter by wire, creating a complete circuit

• A common example is zinc and copper:

  • Zinc is the more reactive metal and forms ions more easily, readily releasing electrons

  • The electrons give the more reactive electrode a negative charge and sets up a charge difference between the electrodes

  • The electrons then flow around the circuit to the copper electrode which is now the more positive electrode

  • The difference in the ability of the electrodes to release electrons causes a voltage to be produced

• The greater the difference in the metals reactivity then the greater the potential difference produced

• The electrolyte used also affects the voltage as different ions react with the electrodes in different ways

• In some chemical cells, the potential difference is only produced until the reactants are used up

Diagram of a simple cell