Ch15(Part2).pptx - Chapter 15(Part 2 Electrode Measurements...

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Chapter 15 (Part 2)Electrode Measurements
Ion-Selective ElectrodesElectrodes that respond preferentially to a single ion species in solutionA membrane separates an inner solution of the ion of interest from the outer solution containing the analyte ionThe difference in concentrations of the ions in the inner and outer solutions produces a voltage differenceThis is a direct measurement, subject to junction potential error
Liquid Based K+Selective Electrode
Liquid Based K+Selective ElectrodeIon-selective membrane in Figure 15-6 is “liquid based” becauseIt contains hydrophobic organic polymer Impregnated with a hydrophobic anionR-in this figure is tetraphenyborate, (C6H5)4B-Impregnated with a selectively binding ligand for the cationThe ligand in this figure is valinomycinThe filling solution contains the target ion C+and a counter ion B-Both at appropriate stoichiometric ratios to each otherBoth at known concentrationThe analyte solution containsThe target ion C+at a to be determined concentrationA counter ion A-at an appropriate stoichiometric ratio to the cationThe identities of the counter ions is theoretically unimportant
Ion Selective Electrode Voltage Measurement

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