Chemical Reaction System Unit Test
Use the dissociation reaction to answer the question.
Fe SCN2+(aq) = Fe3+(aq) + SCN- (aq)
in the reaction. Fe SCN2+ ions are red, Fe3+ ions are pale yellow and SCN-ions are colorless A solution at equilibrium is yellow-orange. The concentration of SCN ions is increased by a moderate amount Which color will the solution most likely become? 1 point)
o orange
O yellow
o red
o colorless
@ Heyo. You must have guessed. You had a 1 in 3 chance of getting it right but didn't.
I have two things. The first is the questions. I have seen many many solutions of SCN^- and they are colorless. They are NOT orange. This is a Le Chatelier's Principle question and not a very good one at that. Le Chatelier's Principle says that if we do something to a system at equilibrium that the system will try to undo what we did to it. SO, if we add SCN^- it will try to use up the added SCN^-. How can it do that? The equilibrium can shift to the left which will use SCN^- and use Fe^3+ and will form more FeSCN^2+. So the end result will be a solution that is more concentrated in FeSCN^+ and less concentrated in Fe^3+. What color will that be? Who knows? Enough SCN^- and the end result will be red. Less than that and you will have red color mixed with the yellow color of the Fe^3+ to give an orange color. So it all depends upon how much SCN^- is added. My best guess is that a MODERATE amount of SCN^- means some Fe^3+ is left and the mixture of yellow and red will produce an orange color. My best guess as to answer the teacher wants is "red". Why? Because the SCN^- is erroneously cited as being orange in the problem and a shift to the right (the wrong way) will definitely produce an orange color. Sorry for getting on my soap box.
@DrBob222 Nerd.
but thanks:D
i think its B: yellow
Anyone have all the answers for this test?
To determine the color change in the solution when the concentration of SCN- ions is increased, we need to understand the reaction and the color of the ions involved.
In the given dissociation reaction:
Fe SCN2+(aq) = Fe3+(aq) + SCN-(aq)
Fe SCN2+ ions are red, Fe3+ ions are pale yellow, and SCN- ions are colorless.
At equilibrium, the solution is yellow-orange, which suggests that the combination of the colors from the Fe SCN2+ (red) and Fe3+ (pale yellow) ions results in the yellow-orange color.
Now, let's reason based on Le Chatelier's Principle. When we increase the concentration of SCN- ions, it will shift the equilibrium towards the reactants to counteract the change. As a result, more Fe SCN2+ ions will be formed, which are red in color.
Therefore, when the concentration of SCN- ions is increased, the solution will most likely become more red in color.
Hence, the correct answer is:
o red