SREEKANTH NAMA, M.PHARM,(Ph.D)
DEPARTMENT OF PHARMACY, JIMMA UNIVERSITY, HAND OUT ON COULOMETRY
Page 1
COULOMETRY
• Introduction
• Principles
• Apparatus and measurement
• Applications of Coulometric methods
INTRODUCTION
• Coulometry is the name given to a group of techniques in analytical chemistry
that determine the amount of matter transformed during an electrolysis reaction
by measuring the amount of electricity (in coulombs) consumed or produced.
• If no extraneous reaction is involved, faraday’s law states that one equivalent of
chemical change occurs at an electrode during electrolysis with the passage of
96485 coulombs of electricity.
• If can assume that there are no competing side reactions (100% current efficiency)
then
Where,
W, is the weight of the substance transformed during electrolysis
Q, is the quantity of electricity, coulombs
M, is the molecular or atomic weight of the substance being oxidized or reduced
Z, is the number of electrons involved in the electro reaction
• It is clear that there is a direct relationship between the weight of material
transformed and the quantity of electricity consumed.
• The application of this relation is known as coulometric analysis, which permits
the quantitative determination if any substances that can be made to under go an
SREEKANTH NAMA, M.PHARM,(Ph.D)
DEPARTMENT OF PHARMACY, JIMMA UNIVERSITY, HAND OUT ON COULOMETRY
Page 2
electrochemical reaction with 100 percent current efficiency. (With out any
extraneous reaction or side reaction)
• Coulometry is an analytical method for measuring an unknown concentration of
an analyte in solution by completely converting the analyte from one oxidation
state to another.
• Coulometry is an absolute measurement similar to gravimetry or titration and
requires no chemical standards or calibration. It is therefore valuable for making
absolute concentration determina