In: Chemistry
Summarize the different of type of indicator electrodes, their definition, characteristics and applications
Indicator Electrode
Indicator electrode is the one at which potential is measured with respect to reference electrode. Any electrode whose potential is to be measured can be used as indicator electrode.
There are four types of indicator electrodes –
1) Metal electrode
Metal electrode develop electric potential as a result of redox reaction at its surface. Platinum (Pt), Gold (Au), Palladium (Pd) , inert metals are responsive to the activities of the oxidized and reduced forms of the redox couple near the electrode surface.
2) Hydrogen electrode
This electrode used in acid base titration. As many organic compounds directly react with hydrogen gas this electrode is having very limited applications.
3) Glass membrane electrode
This electrode is most commonly used electrode. In this electrode involves ion exchange reaction. Generally, the membrane in this electrode is made up of chemically bonded SiO2 and Al2O3.
The glass bulb is filled with solution of HCl & KCl coated with AgCl is inserted as electrode.
4) Quinhydrone electrode
This electrode contains solution of quinones and hydroquinone prepared from quinhydrone.
This electrode consists of an inert metal electrode in contact with quinhydrone crystals and water-based solution. In this electrode the equilibrium attains easily. This electrode is sensitive to high concentration of salt and oxidizing and reducing agents. This electrode is not reliable above pH 8.