Electrochemical Cells (Edexcel GCSE Chemistry)

• A simple 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 voltage produced
• The electrolyte used also affects the voltage as different ions react with the electrodes in different ways
• Cells produce a voltage until one of the reactants is used up

Simple cell made with Cu and Mg. These metals are further apart on the reactivity series than Cu and Zn and produce a greater voltage