Determination of pH of unknown solution using Glass electrode. pH of unknown solution is determined by measuring potential of solution using glass electrode. Here glass electrode is coupled with standard calomel electrode which acts as a refrence electrode. Both electrodes are dipped in a solution whose pH has to be determined and is connected to the voltmeter. once it is connected to the voltmeter the potential is measured and that potential is known as Cell potential. So here the glass electrode acts as an anode and the standard calomel electrode acts as cathode. The cell which is represented diagrammatically can also be represented as Ag AgCl which is the internal reference electrode or glass electrode (0.1M) Glass Test Solution this entire glass electrode is connected to calomel this is the salt bridge KCL HG2Cl2 HG Since calomel electrode acts as cathode the reduction reaction occurs at the cathode. the solution is of unknown pH thus the solution is acidic. 2H+ + 2e- gives rise to H2 By knowing the calomel electrode potential, glass electrode potential, pH of unknown solution can be determined as cell potential is by E-cathode minus E-anode by substituting the cathode and anode we get equal to e standard calmode potential minus e glass potential is equal to standard calomel electrode is given by E0G - 0.0591pH which are constant by equating the pH we get E cell + E 0 G minus E sce divided by 0.0591 E cell is determined E0G G is a constant E standard calomel electrode is also constant substituting all these values pH of unkown solution is determined.