Chemistry Forum

The reaction below competes with the formation of the FeSCN₂+ complex
Fe₃+(aq) + 4Cl-(aq)↔ FeCl-4(aq)
Yellow Colorless
Explain what would happen to the color of a dilute solution containing FeCl-4 if

A. You added a solution containing silver ion, Ag+ (silver ion reacts with chloride ion in solution to form the precipitate AgCl.)



B. You added a solution of sodium chloride, NaCl.



C. You added concentrated HCl.



D. You added concentrated H₃PO₄

Your question is not quite clear. Please make a search on iron rhodanide complexes and you will fing plenty of information since it's a very common reaction.
http://www.google.com/#hl=en&source=hp& ... 0d3c90c6fc

Obviously, othe anions will compete with rhodanide. When you add them (chloride in your case), the rhodanide gets substituted and the salt is loosing color. When you remove them by Ag+ the color returns.
Make sure check out this ref http://en.wikipedia.org/wiki/Thiocyanate