in today's video we're going to take a look at electrolysis so after a quick look at what it is more generally we'll see how we can use it to separate the elements in insoluble ionic compounds like lead bromide before we see how it works though you need to be familiar with the equipment we use as you could be asked to draw or label it in the exam first up we need some kind of Beaker in which we place our electrolyte and an electrolyte is just a liquid or solution that contains an ionic compound with the important point being that the ions in the electrolyte are free to move so if our compound was soluble like copper sulfate then we'd just dissolve it in water and that aquous copper sulfate would be our electrolyte however if it was insoluble like lead bromide then would have to melt it to get a molten liquid CU that's the only way to make sure our ions would all be free to move around so if we change our electrolyte to be molten lead bromide then it would contain positive lead ions and negative bromide ions both of which would be free to move about next up we need our electrodes which are solid conductors and generally made of metal or Carbon on the right we have the positive electrode which you call the anode and on the left the negative electrode called the cathode then lastly we need to join the electrodes with some wire so that the electrons can flow between them and add some kind of power supply like a battery to drive that flow of electrons now the word electrolysis literally means splitting up with electricity and that's exactly what it does by using our battery to pass an electric current through the electrolyte which in our case is more lead bromide we can separate out the lead and the bromine the way this works is that the negative bromide ions will be attracted to the positive anode and when they get there they'll be discharged which just means that they go from a Charged ion to a neutral atom and in bromine's case this will cause the atoms to pair up and form bromine gas which can then float off meanwhile the positive lead ions will be attracted to the negative cathode and again be discharged this time to form pure lead which will then fall to the bottom and form a layer of molten lead now the last thing we need to point out is that the ions are actually being oxidized and reduced at the electrodes in our example at the anode the bromide ions are being oxidized to bromine and lose one electron each in the process which we written out here as a half equation meanwhile at the cathode the lead ions each combining with two electrons and so being reduced to form pure lead so really what's happening overall is that the electrons from the bromide ions are being passed to the positive anode and then being transported along the wire around to the cathode using the power of the battery then these electrons are being given to the lead ion turning it into pure neutral lead so we're basically using electricity to convert the ions in a compound back into into their pure Elemental forms by transferring the electrons from the negative ions to the positive ions in the next two videos we'll take a look at the electrolysis of metal oxides to extract pure metal and the electrolysis of acurate solutions if you haven't heard yet you can find all of our videos on our website Cognito dog you'll also find questions flashcards EX exam style questions and past papers and we track all of your progress so that you always know what to study next so sign up for free by clicking here or browse our playlist here on YouTube