FeSCN2+ -> Fe3+ + SCN-

Question

Solution is initially dark red. If some Ag+ is added to form AgSCN. what happens to position of equilibrium? what happens ot the color?

Answer 1

AgSCN is a white ppt. Adding Ag^+ will ppt AgSCN and that removes the SCN^- from solution which will shift the equilibrium to the right. If enough Ag^+ is added, all of the FeSCN^+2 complex (red) will be used up and you will be left with a white ppt of AgSCN + iron(III) ions.