Question
I had an equilibrium laboratory and had to answer a few questions after the lab. Here are 2 questions I can't seem to know how to answer.
1. Explain in your own words why a saturated solution in contact with some undissolved solid is considered to be an equilibrium situation?
2. Rationalize how the addition of the silver nitrate to the Fe/SCN equilibrium system had an effect even though neither Ag nor NO3 appears in the equation shown in the text.
Attempt:
For number 2 I was going to write that the Ag ion will replace the Fe in FeSCN and the NO3 will do the same but with the Fe ion?
1. Explain in your own words why a saturated solution in contact with some undissolved solid is considered to be an equilibrium situation?
2. Rationalize how the addition of the silver nitrate to the Fe/SCN equilibrium system had an effect even though neither Ag nor NO3 appears in the equation shown in the text.
Attempt:
For number 2 I was going to write that the Ag ion will replace the Fe in FeSCN and the NO3 will do the same but with the Fe ion?
Answers
DrBob222
#1. In as few words as possible, the solid is continuing to dissolve to form a solution and material in the solution is continuing to ppt; therefore, the material in solution is constant and the solid is constant. That's equilibrium.
#2. You didn't write the equations in your text but I assume it is
Fe^3+ + SCN^-= ==> FeSCN^2+
The reason equilibrium is upset is because Ag^+ reacts with SCN^-. You can look up what it forms. If you pull SCN^- out then the Fe/SCN equilibrium shifts to the right.
#2. You didn't write the equations in your text but I assume it is
Fe^3+ + SCN^-= ==> FeSCN^2+
The reason equilibrium is upset is because Ag^+ reacts with SCN^-. You can look up what it forms. If you pull SCN^- out then the Fe/SCN equilibrium shifts to the right.