Analytical applications of second order electrodes

Abstract

Second order electrodes of silver-silver bromide, silver-silver iodide, silver thiocyanate, silver-silver chromate and silver-silver tetraphenylboron have been investigated. Suitable electrodes for the last two systems could not be prepared. The indicator electrodes were coupled with a saturated calomel reference electrode and the potentials of various solutions measured. The response of the electrodes to anion activities was determined and compared with calculated potentials. The effects of ionic strength and diverse ions on the observed potentials were determined. Results on selected samples indicate that direct potentiometric measurements can be used for the determination of bromide, iodide and thiocyanate ions in aqueous solution. In the concentration range of 1 × 10 −1 — 1 × 10 −4 M, measurements can be made with an accuracy comparable to that obtained in usual potentiometric work.