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Unformatted text preview: 1 DETERMINING FLUORIDE IN TAP WATER USING THE FLUORIDE ION SELECTIVE ELECTRODE Background Reading: Harris, 7 th ed., Chap. 15. Skoog, West, Holler and Crouch, 7 th ed., Chap. 19. Introduction The fluoride electrode based on a solid LaF 3 membrane is one of the few ion "selective" electrodes that is truly selective for a particular ion, in this case F- . A potentiometric technique, it is routinely used in analytical laboratories and in the field as a cost-effective, reliable method for F- determination. The electrode itself is made from a single crystal of LaF 3 sealed into a plastic tube. The LaF 3 acts as a membrane which selectively exchanges and transports F- ions. The cavity inside the electrode is filled with a solution containing F- and Cl- ions, and an AgCl coated Ag wire dips into this to make an internal reference electrode, just as in the pH electrode. A separate reference electrode completes the cell. The response of the electrode to F- under the right conditions is very close to ideal...
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This note was uploaded on 03/18/2012 for the course CHM 3120L taught by Professor Dr.gormin during the Spring '12 term at Florida State College.
- Spring '12
- Analytical Chemistry