TRAVISTRA

 GLASS ELECTRODE It is a secondary reference electrode that produces a constant and reproducible electrode potential. It is an ion-selective electrode used with other reference electrodes to generate a potential difference. Construction It is made up of a special glass of relatively low melting point and high electrical conductivity, in the form of a sealed glass tube filled with 0.1M HCl, a platinum wire is inserted into it, to make electrical contact. The glass electrode is represented as Pt| 0.1M HCl | Glass | H+    The H+ ion concentration inside the electrode is constant. When the electrode is immersed into a solution of unknown H+, it becomes sensitive to the outside concentration in the solution. Such a sensitivity arises because of the difference between the H+ ion concentration inside and outside.       The electrode potential of the glass rod is : EG = EG0 + 0.0591 log [ H+ ]     EG = EG0 - 0.0591 pH  The glass electrode i...

CALOMEL ELECTRODE  It is a secondary reference electrode. It consists of a glass tube at the bottom of which is kept, Hg2Cl2, and a solution of KCl. A Pt wire is dipped into the Hg layer used for making electrical contact.  The side tube is used for making electrical contact with the salt bridge. The electrode is represented as Hg| Hg2Cl2| KCl. Electrode reaction is represented as :    2Hg + 2 Cl    ---->       Hg2Cl2 + 2 e- The potential of the electrode depends upon the concentration of KCl solution.  Electrode potential if saturated calomel electrode (SCE) is 0.2422V. Determination of electrode potential (E⁰) using calomel electrode  The electrode whose potential is to be found out is connected with a saturated calomel electrode through a salt bridge internally and the emf of the cell is determined using a potentiometer. 

 ELECTRODES AND TYPES OF ELECTRODES ELECTRODES  Electrodes are materials which  is  a good conductor of electricity and chemical reaction  TYPES OF ELECTRODES 1. Metal-Metal ion electrode e    In this electrode a metal rod is immersed in its own salt solution      eg: Zn (znso 4 )   2. Metal-metal insoluble salt electrode     In this electrode, metal is coated by insoluble salt  and it is immersed in a solution containing a common   ion    eg: calomel electrode    3. Gas electrode      In this electrode, an inert metal is immersed in a solution containing ions of the gas is continuously bubbled through the solution eg: Standard Hydrogen Electrode 4. Ion-selective electrode        It is a sensor that converts the concentration of a specific ion dissolved in a solution into an electric potential  eg: Glass Electrode 5. Redox Electrode  ...