How does KCl effect the equilibrium system: Fe^3+(aq) + SCN^-(aq) [equilbrium symbol] Fe(SCN)^2+(aq)?

Question

The colour change was that it began to get clearer. I need to determine the direction of the equilbrium shift and the reason for this shift.
I know that Fe^3+ is colourless, SCN^- is colourless, and Fe(SCN)^2+ is blood red.

Answer 1

KCl is a salt and it disassociates in water into

KCl --> K+ and Cl-

The K+ competes with the Fe3+ for the SCN- ion
K+ and SCN- --> KSCN (which isn't red)

So because of this competition, the reaction you have written doesnt proceed to the right as it should go. On the contrary, when you add KCl, another reaction takes place that drains the SCN- that would be otherwise available to form the red Fe(SCN). So, as you KCl, the solution turns less red.

The direction is that equilibrium shifts to the left.

Answer 2

I disagree with Jared. KSCN is a salt and is fully dissociated in water.

But chloride cam complex Fe3+, which will indeed shift the equilibrium away from FeSCN 2+