Question

I would like to ask a question about chemical cell and eletrolysis

When it is the negative eletrode, how can I distinguish that I should write the half equation by seeing the metal eletrode or the solution?

Answer 1

First of all since it is the negative electrode, it is cathode in case of electrolysis.at cathode always reduction occurs so you have to write reduction equation or reactionsecondly if the electrode is inert like platinum or graphite than consider only solution for electrolysis.but if the electrode is active like that of silver , copper or zinc than compare the reduction potential of the species in solution and of electrode , the more positive the reduction potential the more will be its tendency to get reduce. thus write the chemical equation for the one having more positive reduction potential.