Unit 5: Electrochemical Methods of Analysis

Semester 1

BP102

Introduction to Electrochemical Methods of Analysis

Unit 5 introduces modern instrumental methods of analysis. These techniques rely on electrical properties (Conductance, Potential, Current) rather than color change. You will learn about Conductometric titrations for turbid solutions, Potentiometric titrations for pH measurements, and Polarography for trace analysis.

Syllabus & Topics

1Conductometry: Introduction, Conductivity cell
2Conductometric Titrations: Principles & Applications
3Potentiometry: Electrochemical cell, Reference Electrodes (SHE, Calomel, Ag/AgCl)
4Indicator Electrodes: Metal electrodes, Glass Electrode
5Potentiometric Titration: Methods to determine end point
6Polarography: Principle, Ilkovic Equation
7Construction & Working of Dropping Mercury Electrode (DME) & Rotating Platinum Electrode

Learning Objectives

Explain the principle of Conductometric titration.

Draw the diagram of Standard Hydrogen Electrode (SHE) and Calomel Electrode.

Describe the construction and working of Glass Electrode.

Understand the principle of Polarography and Dropping Mercury Electrode.

Derive the relationship between conductance and concentration.

Frequently Asked Questions (FAQs)

Q1. What is Conductometry?

Conductometry measures the electrical conductivity of an ionic solution. During a titration, changes in the concentration or type of ions cause changes in conductance, which are used to detect the end point.

Q2. What is a Standard Hydrogen Electrode (SHE)?

The Standard Hydrogen Electrode (SHE) is the primary reference electrode. It consists of a platinum foil coated with platinum black, dipped in 1 M HCl, with hydrogen gas bubbled at 1 atm pressure. Its electrode potential is arbitrarily assigned a value of 0.00 V.

Q3. What is an Indicator Electrode?

An indicator electrode responds to changes in the activity (concentration) of a specific ion in solution. Example: A glass electrode responds to H⁺ ion activity and is used for pH measurement.

Q4. What is Polarography?

Polarography is an electrochemical analytical technique that uses a Dropping Mercury Electrode (DME) to analyze solutions containing reducible substances. A graph of current versus voltage (polarogram) is obtained, which is used for both qualitative and quantitative analysis.

Q5. What is the Ilkovic Equation?

The Ilkovic equation relates the diffusion current (iᵈ) in polarography to the concentration (C) of the analyte. It forms the basis of quantitative analysis in polarographic methods.