Transcript Voltammetry

Voltammetry
Chapter 25
CHM 411
Spring 2013
I. Introduction
• Voltammetry – cell current measured as
function of applied potential
II. Instrumentation
• 3 electrode cell with
potentiostat
– Working electrode
– Reference electrode
– Counter Electrode
• Potential waveforms
III. Hydrodynamic Voltammetry
• Involves stirring a
solution
A. Electrode in a stirred solution
• Points of interest
– Convection brings analyte to
diffusion layer but only
diffusion can carry it to
electrode
– δ is constant for constant
stirring rate
– δ ≅ 10-2 – 10-3
B. What does the limiting current depend on?
1.
2.
3.
Rate of the arrival of analyte
Electrode area
Number of electrons
transferred in the reaction
B. What does the limiting current depend on?
• Current is diffusion
limited
C. Applications of Hydrodynamic Voltammetry
1. HPLC Detection
2. Voltammetric Sensor
C. Applications of Hydrodynamic Voltammetry
3. Enzyme based
4. Fundamental Studies
IV. Cyclic Voltammetry
• Read the article
V. Polarography
• Voltammetry at
dropping mercury
electrode
• Differential Pulsed
Polarography