Chemistry Form 4: Chapter 6 - Electrolysis of Lead (II) Bromide

• Electrolysis is a chemical process where a substance in its molten state or in an aqueous solution decomposed by electric current.
• This involves conversion of energy from electrical energy to chemical energy.
• Electrodes are the strips of metals inserted into electrolyte for conduction of electricity. he metal electrode connected to the positive terminal of the battery is called the anode (+). The metal electrode connected to the negative terminal of the battery is called the cathode (-).
• Electrolytic cell is the complete set-up for electrolysis. This consists of the vessel containing the electrolyte, anode, cathode, battery and  wires. 

At the Cathode	At the Anode
Observation When electricity is flowing, a silvery deposit of lead metal forms on the cathode. In fact, as it is molten, it is more likely to drip off in a molten blob.	Observation When electricity is flowing, brown fumes of bromine gas are seen at the anode.
Half equation Pb2+ + 2e ---> Pb	Half equation 2Br- ---> Br2 + e
Explanation The lead(II) ions, as they are positive, move to the negative cathode, where each ion gains two electrons to form a lead atom. Any reaction at a cathode involved  a gain in electrons. This is called reduction or more exactly, cathodic reduction .	Explanation The bromide ions, as they are negative, move to the positive anode, where each loses an electron to form a bromine atom. Then two of these newly formed atoms combine to form bromine gas. Any reaction at an anode involves a loss of electrons.