FeSCN2+ -> Fe3+ + SCN-
Solution is initially dark red. If some Ag+ is added to form AgSCN. what happens to position of equilibrium? what happens ot the color?
Well, when Ag+ is added to the solution, it will react with the SCN- ions to form AgSCN. This means that some of the SCN- ions will be removed from the solution. According to Le Chatelier's Principle, when a component of the reaction is removed, the equilibrium shifts to the side that will replenish that component. In this case, more SCN- ions will be formed to replace the ones that were consumed, causing the equilibrium to shift towards the reactants (FeSCN2+).
Now, as for the color, the FeSCN2+ complex ion is responsible for the dark red color of the solution. Since the formation of AgSCN reduces the concentration of SCN- ions, there would be a decrease in the concentration of FeSCN2+ as well. As a result, the intensity of the dark red color would decrease. So, if we were to compare it to a clown's red nose, it would be like poking it with a pin and deflating it a little bit.
When Ag+ is added to the solution containing FeSCN2+, the Ag+ ions react with the SCN- ions to form AgSCN. This reaction can be represented by the equation:
Ag+ + SCN- -> AgSCN
The addition of Ag+ ions causes a shift in the equilibrium of the original reaction, FeSCN2+ -> Fe3+ + SCN-. According to Le Chatelier's principle, the position of equilibrium will shift to the left.
By adding Ag+ ions, it increases the concentration of SCN- ions, which will react with Fe3+ ions to form FeSCN2+ as per the original equation. This shift to the left leads to an increase in the concentration of FeSCN2+ and a decrease in the concentrations of Fe3+ and SCN- ions.
As for the color, the initial solution is dark red due to the presence of FeSCN2+ ions. When the position of equilibrium shifts to the left, the concentration of FeSCN2+ increases, resulting in a deeper red color. However, the reaction with Ag+ ions causes the SCN- ions to decrease in concentration, leading to a decrease in the production of FeSCN2+ and a lighter red color overall.
To determine what happens to the position of equilibrium and the color when Ag+ is added to form AgSCN, we need to consider the Le Chatelier's principle. This principle states that when a system at equilibrium is subjected to a change, it will tend to counteract that change and establish a new equilibrium.
In the given equilibrium reaction:
FeSCN2+ ⇌ Fe3+ + SCN-
The forward reaction is the formation of FeSCN2+ (dark red color), and the reverse reaction is the dissociation of FeSCN2+ to form Fe3+ and SCN-.
When Ag+ is added to form AgSCN, the added Ag+ reacts with SCN- to form AgSCN, which is a white precipitate. This reaction consumes some of the SCN- ions from the solution, shifting the equilibrium towards the products (Fe3+ and SCN-), according to Le Chatelier's principle.
So, the position of equilibrium shifts to the right, favoring the formation of more Fe3+ and SCN-. As a result, the concentration of Fe3+ and SCN- will increase, and the concentration of FeSCN2+ will decrease. Since FeSCN2+ contributes to the dark red color in the solution, the color of the solution will become lighter or possibly change completely depending on the concentration of Ag+ added.
In summary, when Ag+ is added to form AgSCN, the equilibrium shifts to the right, leading to an increase in the concentration of Fe3+ and SCN-, a decrease in the concentration of FeSCN2+, and a lighter or different color in the solution.