Which ion cause a shift when adding fecl3 to fe(scn)3
Answers
Since Fe3+ is on the reactant side of this reaction, the rate of the forward reaction will increase in order to "use up" the additional reactant. This will cause the equilibrium to shift to the right, producing more FeSCN2+.
Answer:
Consider the following system under equilibrium:
Fe3+(aq)colorless+SCN−(aq)colorless⇌FeSCN2+(aq)red(15.8.1)
If more Fe3+ is added to the reaction, what will happen?
According to Le Chatelier's Principle, the system will react to minimize the stress. Since Fe3+ is on the reactant side of this reaction, the rate of the forward reaction will increase in order to "use up" the additional reactant. This will cause the equilibrium to shift to the right, producing more FeSCN2+. For this particular reaction, we will be able to see that this has happened, as the solution will become a darker red color.
There are a few different ways to state what happens here when more Fe3+ is added, all of which have the same meaning:
equilibrium shifts to the right
equilibrium shifts to the product side
the forward reaction is favored
What changes does this cause in the concentrations of the reaction participants?
Fe3+
Since this is what was added to cause the stress, the concentration of Fe3+ will increase. (A shorthand way to indicate this: [Fe]3+↑ (Reminder: the square brackets represent "concentration")
SCN−(aq)
Equilibrium will shift to the right, which will use up the reactants. The concentration of SCN−(aq) will decrease [SCN]−↓ as the rate of the forward reaction increases.
FeSCN2+
When the forward reaction rate increases, more products are produced, and the concentration of FeSCN2+ will increase. [FeSCN]2+↑
How about the value of Keq? Notice that the concentration of some reaction participants have increased, while others have decreased. Once equilibrium has re-established itself, the value of Keq will be unchanged.