What are the principles of operation for a chloride analyzer that generates silver ions as part of its reaction mechanism?

• A. Potentiometry and amperometry
• B. Amperometry and polarography
• C. Coulometry and potentiometry
• D. Amperometry and coulometry

Answer: (D)

The method hinges on generating the argentometric titrant, silver ions, by electrolysis and then measuring the current to quantify the reaction with chloride. Silver ions are produced in a controlled way so that the amount of silver generated is known from the charge passed (coulometry). As those silver ions react with chloride to form insoluble AgCl, the extent of this reaction is tracked by the current signal, which is the amperometric part. In essence, a known quantity of silver ions is produced and their consumption by chloride is measured as a current, linking the chloride concentration directly to the measured charge/current. Other approaches that rely solely on voltage potential (potentiometry) or a different no-current endpoint method don’t match how this silver-generation chloride analyzer operates.