Electrochemical Methods of Analysis Kuleswor, Viswa Vidylaya Path Prof. Dr. Raja Ram Pradhananga Kuleswor, Viswa Vidylaya Path Kathmandu, Nepal Elecrtoranlytical Technique- RajaRam

Elecrtoranlytical Technique- RajaRam Introducction Instrumental Techiques of Analysis Speoctroscopy Electrochemistry Chromatography Electrochemical Techniques Conductometry Potentiometry Amperometry and Coulometry Voltametry Elecrtoranlytical Technique- RajaRam

Electroanalytical Methods Analytical techniques based on the electrochemical measurements are often refer to as electrochemical methods of analysis or simply as Electroanalytical methods. This method of analysis involves the measurement of current, voltage or resistance alone or in combination. Sometime measurements are done as a function of time. Different Electroanalytical methods are given below. Elecrtoranlytical Technique- RajaRam

Electroanalytical Methods Interfacial Methods Static Methods (I=0) Dynamic Methods (I > 0) Bulk Method Conductometry Elecrtoranlytical Technique- RajaRam

Electroanlytical Methods I Static Method ( I=0) Potentiometry pH-metry Ion-selective electrode Potentiometric Titration Elecrtoranlytical Technique- RajaRam

Electroanlaytical Methods II Dynamic Method ( I > 0 ) Controlled Potential Voltametry Amperometry Constant current Electrogravimetry Coulometry Elecrtoranlytical Technique- RajaRam

Basic Electrical Measurements Principle of Electrochemical Method of Analysis Basic Electrical Measurements Resistance, R Ohms Law V = IR Voltage, V Current, I These electrical properties are measured alone or in combination for analysis. Additional electro-analytical techniques are possible if these electrical properties are measured as a function of time. Elecrtoranlytical Technique- RajaRam

Elecrtoranlytical Technique- RajaRam Conductance Measurement 1/R is measured : Direct Conductance Analysis 1/R versus volume of titrant: Conductometric titration Potentiometry E is measured zero current,(I = 0) i. pH- metry ii. Ion selective potentiometry E versus volume of titrant potentiometric titration Voltametry: i versus E Amperometric Titration: i versus volume of titrant Electroctrogravimetry : Mass of material deposited is determined Coulometry: Current x time (Coulomb) Elecrtoranlytical Technique- RajaRam

Pioneers of Electrochemical Principles Svante Arrhenius M. Faraday Georg Ohm Nobel Prize in 1903 Pioneers of Electrochemical Principles Walter Nernst Jaroslav Heyrovský Nobel Prize in 1920 Elecrtoranlytical Technique- RajaRam Nobel prize in 1959

Elecrtoranlytical Technique- RajaRam Georg Ohm Ohm’s Law The amount of current passing through the conductor is proportional to the electric potential applied. V = I R R = Resistance in Ohms (Ω) Conductance, S = 1 / R Ω -1 Ohms-1 (Mohs) S, Siemens Elecrtoranlytical Technique- RajaRam

Elecrtoranlytical Technique- RajaRam Syllabus The following Electroanalytical techniques are included in Analytical Chemistry of Biochemistry 4th Semester of PU 1. Conductometry 2. Potentiometry 3. Amperometric Titration 4. Coulometry Titration 5. Polarography Elecrtoranlytical Technique- RajaRam

Main Branches of Electroanalytical Chemistry 1. Conductometry : Measure the conductance of a solution. Direct conductometry and conductometric titration. 2. Potentiometry: Measure the potential of electrochemical cells without drawing substantial current pH measurements, ion-selective electrodes, potentiometric titration 3. Amperometric Titration: Measures current as a function of titrant. 4. Coulometric Titration: Measures the quantity of charge required to drive an electrolytic oxidation/reduction to completion Polarography: Measures current as a function of applied potential in a dropping mercury electrode. Potentiometric titration endpoint determination has several advantages, including applicability to turbid solutions. KF uses bipotentiometric endpoint determination with Pt electrodes. Elecrtoranlytical Technique- RajaRam

Elecrtoranlytical Technique- RajaRam Svante Arrhenius Nobel Prize in 1903 For the Theory Electrolytic Dissociation Electrolytes when dissolved in water they split into charge particles called ions Cations (+) Anions (-) Strong Electrolytes Weak Electrolytes Non- electrolytes Elecrtoranlytical Technique- RajaRam

Elecrtoranlytical Technique- RajaRam Jaroslav Heyrovský Nobel prize in 1959 For the development of polarographic technique of analysis Elecrtoranlytical Technique- RajaRam

Elecrtoranlytical Technique- RajaRam M. Faraday Faraday’s Laws of Electrolysis Faraday Ist Law : The mass of the substance discharge at the electrode during electrolysis is directly proportional to the quantity of charge passed through the electrolyte. w =zct Faraday II : The masses of different substances discharged at the electrode by the same quantity of electricity are proportional to their chemical equivalent w/E = constant Elecrtoranlytical Technique- RajaRam

Elecrtoranlytical Technique- RajaRam Walter Herman Nernst N Nobel Prize in Chemistry 1920 For outstanding contribution in chemistry. How the electrode potential vary with concentration Walter Nernst(1864-1941) Elecrtoranlytical Technique- RajaRam

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