chem - asap
posted by Smarth .
i combined agno3 with 25ml of tap water, and it turned faint blue
which ion is present in trace amounts in tap water but not in distillied water? explain. what is the source of the ion in the tap water?
I would have expected a white turbidity due to AgCl (2AgNO3 + Cl2 ==> 2AgCl(s)). The source of the ppt is from the small amount of chlorine used in most city water systems to purify water for purposes of drinking. The faint blue color you saw could be due to two things but I have no idea which one it is. I would need more information for that.
1. AgCl decomposes in light to form Ag(s) + Cl2 and the Ag(s) metal is colloidal and violet in color.
2. The AgCl CAN be blue if the size of the solid particles is right.
I suspect #1 is more probable than #2.
The Cl2 reacts with water to form the Cl^- and OCl^-. It's the Cl^- that reacts with the Ag^+ to form AgCl(s).