Study Set Content:
It is used to measure the potential of the analyte solutions comparing with that of the reference electrode.
2.INDICATOR ELECTRODE
Its potential is () to ion concentration
directly proportional
ex. of INDICATOR ELECTRODE
Hydrogen Electrode, Glass Electrode.
Antimony – antimony oxide electrode
Two classes of indicator electrodes
1. Metal Indicator Electrodes
2. Ion-selective Electrodes
These develop electric potential in response to redox reaction on the metal surface.
METAL INDICATOR ELECTRODES
used as metal indicator electrodes
Platinum or Au
They are mainly classified into three types of electrodes used in the potentiometry:
1. First kind electrodes
2. Second kind electrode
3. Third kind electrodes
Composed of the metal rod immersed in its metal solution. These electrodes respond to the ionic activity of the electrode
First kind electrodes
These are composed of the metal wires coated with the salt precipitates. These electrodes respond to the changes in the ionic activity through the formation of the complex.
Second kind electrode
These electrodes are also known as inert electrodes and redox electrodes. They are composed of inert metal electrode immersed in the redox solution.
Third kind electrodes
Second kind electrode
ex. Ag/AgCl/KCl
Hg/Hg2Cl2/KCl
First kind electrodes
Ex. Silver electrode dipped in the silver nitrate solution
Copper Electrode dipped in the copper sulphate solution
Third Kind electrodes
Ex. Pt H3 Electrode
These are composed of ion-selective membrane by which the ions crosses, and it creates the imbalance.
ION SELECTIVE INDICATORS
ex. of ION SELECTIVE INDICATORS
Glass membrane electrode
Antimony – antimony oxide electrode
TYPES OF POTENTIOMETRIC TITRATIONS
• Acid-base titration
• Redox Titration
• Complexometric Titration
• Precipitation titration
- Glass/ calomel electrode for determination of pH.
ACID-BASE TITRATION
ex. of ACID-BASE TITRATION
Ex. Titration of HCl with NaOH
Titration of CH3COOH with NaOH
Membrane electrodes for the determination of the halogen using silver nitrate reagent.
PRECIPITATION REACTION
ex.of PRECIPITATION REACTION:
ex. Titration of Mixture of Cl & Br & I with AgNO3
