The method employed is the electrolytic refining of copper when the impure copper is made from the anode in an electrolyte bath of copper sulphate, CuSO4, and sulfuric acid H2SO4. The cathode is a sheet of very pure copper. As current is passed through the solution, positive copper ions, Cu2+, in the solution are attracted to the negative cathode, where they take on electrons and deposit themselves as neutral copper atoms, thereby building up more and more pure copper on the cathode. Meanwhile, copper atoms in the positive anode give up electrons and dissolve into the electrolyte solution as copper ions.