What are everyday applications for the chloride solubility rule?

I am doing experiment about precipitation and separation of group I ions. The chlorides of Pb2+ and Ag+ are all insoluble in cold water, they can be removed as a group from solution by adding HCl. The equations are:
Ag+(aq) + Cl-(aq) rightarrow AgCl(s)
Pb2+(aq) + 2Cl-(aq) rightarrow PbCl2(s)

My question is how this experiment relates to daily life experience?

Maybe these aren't daily experiences, but:
  • Chloride is regularly monitored in municipal water supplies- especially in coastal areas. High chloride levels lead to salt poisoning (which was a principal cause of death in early America- it contributed to the failure of the Jamestown colony! [Earle]. The precipitation reaction with silver is the basis for several classical chemical analyses used to monitor chloride levels, and is also a quick spot test for chlorides (try adding a couple of drops of silver nitrate to your tap water!)
  • Silver is very expensive and is recycled whenever possible. The silver chloride precipitation reaction allows silver to be separated from photographic and plating solutions and reclaimed.
  • If adding salt to a water sample causes it to cloud, it is probably heavily contaminated with silver, mercury, or lead.
  • The lead reaction has some implications for soldering; clean a high-chloride flux off your circuit board or the HCl will react slowly with the solder, producing lead(II) chloride.
  • You have some insight now into how minerals like horn silver and cotunnite form and wether.
  1. C. V. Earle, Environment, Disease, and Mortality in Early Virginia, in The Chesapeake in the Seventeenth Century: Essays on Anglo-American Society, eds. T. W. Tate, D. L. Ammerman, W. W. Norton, New York (1979).

Author: Fred Senese senese@antoine.frostburg.edu

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