c ELECTROLYSIS OF LEAD BROMIDE There are very few suitable low melting point salts Lead bromide has a low melting point and makes an interesting electrolysis experiment Potassium bromide may have too high a melting point 682oC to melt easily The lead bromide is melted in a 100 mL hard glass beaker or in a crucible The carbon electrodes are supported by a strip of wood with two holes bored 2 cm apart for the electrodes Connect crocodile clips to the rods and complete the circuit with a torch bulb to indicate when a current is flowing and a 12volt torch battery or cells wired in series The electrodes can be labelled positive and negative The only ions present in this melt are the bromide and lead ions Bromine is readily seen coming off at the positive electrode which is the anode The fact that bromine appears only at the positive electrode helps in the understanding of the existence of a negative bromide ion Lead has both a lower melting point and a greater density than lead bromide and therefore appears as a melt at the bottom of the beaker The small globule of lead which accumulates at the negative electrode the cathode can be seen after about 10 minutes of electrolysis Decant off the molten lead bromide carefully into another crucible The electric current has split up crystalline lead bromide into bromine gas and lead metal