Final answer:
In chloride analysis, the testing can include adding 6 M HCl to identify insoluble chlorides for qualitative analysis, or using redox titrimetry where direct current induces migration and oxidation of chloride ions for quantitative measurement of chlorine residual by titrating with Na2S2O3.
Step-by-step explanation:
The testing that refers to the migration of chloride ions onto a medium for the performance of chloride analysis is a process which can involve qualitative and quantitative methods. One such method is the addition of 6 M HCl to precipitate insoluble chlorides like AgCl, PbCl2, and Hg2Cl2 for qualitative analysis. Another method involves passing a direct current of electricity through a solution of NaCl, which causes the chloride ions to migrate to the positive electrode and undergo oxidation to gaseous chlorine, corresponding to a quantitative analysis like redox titrimetry. In the determination of total chlorine residual in public water supplies, chloride ions are part of the chemical species that are measured using a method that involves the oxidizing power of chlorine to convert iodide to triiodide (I3-), which is then titrated with Na2S2O3 using starch as an indicator.