Question

Consider the following reversible chemical reaction. Imagine that you have prepared a solution of FeSCN2+ which is initially blood red in color.

Answer the following questions about the equilibrium shifts and color changes that result from various chemical changes.

Fe3+ (aq) + SCN-(aq) FeSCN2+(ag)

First, several drops of concentrated iron nitrate (Fe(NO3)3) are added to the red solution. As a result, the solution will
Options:
A. turn darker red
B. remain the same color
C. turn yellow
D. become colorless

Answer 1

Upon adding concentrated iron nitrate to the FeSCN2+ solution, the reaction equilibrium shifts right, leading to an increased concentration of FeSCN2+ and a darker red color.

Step-by-step explanation:

When several drops of concentrated iron nitrate (Fe(NO3)3) are added to a solution of FeSCN2+, which is initially blood red in color, the color will turn darker red. This is due to Le Chatelier's Principle, where addition of more Fe³⁺ (which is an iron ion and also a reactant in the equilibrium) will cause the equilibrium to shift to the right in order to minimize the stress of the added reactant. Consequently, the rate of the forward reaction increases, leading to the production of more FeSCN²⁺ and a darker red coloration as the concentration of the complex increases.