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Electrode Measurements – Ch 15
Applications to potentiometric titrations, pH
electrodes, quantitative measurements
using ion-selective electrodes, etc.
There are electrodes available for each of the 4
titration categories covered in this class:
•Acid-base – pH electrodes
•Precipitation – Ag/AgCl electrode, Ag+ specific
ion electrode
•Complexiometric – Ca2+ specific ion electrode
•Redox – Pt electrode, Saturated Calomel
Electrode (SCE)
Potentiometric Titrations (Sec. 10-4)
Finding the Endpoint Numerically
1st der. =
2nd der. =
How Ion-Selective Electrodes Work
(Sec. 15-3 – 15-5)
Ideally responds to only the analyte ion in a solution.
Produce a voltage because of a charge difference that
develops inside and outside of the electrode.
A. Liquid-Based Ion-Selective Electrodes
Valinomycin is used
in K-electrodes
Ca2+ Ion-Selective Electrode
pH Measurement with a Glass Electrode
Acid and Alkaline Errors of pH Electrodes
B. Solid-State Ion-Selective Electrodes
Electric Potential Difference for an Ion-Selective Electrode
e.g. pH electrode
Detection Limits and Interferences
Pb limit of detection =