Coulometry: Overview

Coulometry uses the amount of electrical charge needed to fully electrolyze an analyte, to determine its quantity without requiring any analytical standards.

The total charge that is passed during electrolysis is related to the amount of analyte by Faraday's laws of electrolysis.

For efficient coulometric measurements, a charge equivalent to Faraday's constant multiplied by the number of electrons involved in the relevant half-reaction must be supplied per mole of the analyte transformed at the electrode.

Coulometric methods employ either a constant current or a controlled potential.

Constant-current coulometry measures the amount of charge passing through the cell over time while applying a constant current to the system.

In controlled-potential coulometry, a constant potential is applied to the system, and the amount of charge passed through the cell is measured as the current varies over time.