Chapter 3 Electrochemistry

 Introduction

Electrochemistry is branch of chemistry concern with the interaction of electrical and chemical effects

• A large part of this field deals with the study of chemical changes caused by the passage of an electrical current and the production of electrical energy by chemical reaction.

This mentioned methods need values of potential corresponding to very small change in volume of titrant added near the end point for good result. In the immediate area of the end point the concentration of the original reactant becomes very small, and it usually becomes impossible for the ions to control the indicator electrode potential.

What are ELECTROCHEMICAL METHODS OF ANALYSIS?

These are physicochemical methods of analysis which deal with

electrical quantity or property of a solution of the substance to

be analyzed qualitatively or quantitatively.

The measurements are carried out by the use of certain instruments, thus, the methods are also denoted by instrumental methods.

What are the advantages of these methods?

1- Shorten the time required for analysis.

2- Used when classical methods of analysis can not be applied, e.g. In case of colored, turbid, very dilute solutions

Or when there is no suitable indicator.

Electrochemical methods of analysis

in which the analyte participates in a redox reaction or other process.

In potentiometric analysis, the analyte is part of a galvanic cell, which generates a voltage due to a drive to thermodynamic equilibrium. The magnitude of the voltage generated by the galvanic cell depends on the concentration of analyte in the sample solution.

In voltammetric analysis, the analyte is part of an electrolytic cell. Current flows when voltage is applied to the cell due to the participation of the analyte in a redox reaction; the conditions of the electrolytic cell are such that the magnitude of the current is directly proportion 

Formulae For

ELECTROCHEMISTRY

FORMULAS-ELECTROCHEMISTY

Important Terms, Definitions & Formulae

XII Chemistry

CHAPTER 3 - ELECTROCHEMISTRY

1. ElEcathode - Ende 0.059. 1

2. E = E -log n [M] (At 298 K)

3. Ecell Ecell 2.303RT [Anode ion] -log nF [Cathode ion]

4. 0.059 cell -log K. (At 298 K)

n 5. AG -nFE cell

6. R-p== A ΚΑ

7. Conductance:G= 1 R

8. Conductivity Conductance x Cell constant

9. K=-=-(-) =G PRA A

10. Cell constant and is denoted by the symbol G Specific conductance

11. Am

Molarity xx 1000 12.

C

Remember: Unit of Amin above formula is Scm²mol¹¹

13.α= Am

14. K 1-c