I have 3 Questions:

Question

We actually did the lab experiment for this, but I have no idea whether my reasons are correct.
1) For the equilibrium system Fe+3 + SCN- <--> FeSCN+2, what would happen if you add 2 drops of Fe No3?. Which way will the equilibrium shift towards?

I said that it will move forward (shift towards the right side) because Fe NO3 will add more concentration to the reactants. Is that correct?

2)For the equilibrium system Fe+3 + SCN- <--> FeSCN+2, what will have if you add 2 drops of KSCN? Which way will the equilibrium shift towards?
- Again, I have answered this question with a reverse reaction shift (towards left), is that correct? Because I thought that since the reactants needs 2 to react and the products has only one to react, by adding KSCN, the one with less (the reactants) will react faster, thus causing the equilibrium to shift towards the left. Is that true? or am i wrong?

3) For the equilibrium system of Cu(H2o)4 (2+) + 4NH3<--> Cu(NH3)4 (+2) + 4H2O. What will happen if I add concentrated NH3?
- in the experiment, it showed that the the equilibrium shifted towards the reactants. WHY? i don't get this part. More or less can YOU PLEASE explain HOW to find out WHICH concentration has been increased whenever a compound is added to the equilibrium mixture, like the question I had just asked. please thanx

Answer 1

Are you adding Fe(NO3)3 or FeNO3. I don't know of a FeNO3. Adding Fe^+3 will shift the reaction to the right. Adding SCN^- will shift the reaction to the right. With no more information than you have given, I think the third will shift to the right, also. I know that adding concd NH3 to a Cu^+2 forms Cu(OH)2 initially. Further addition of NH3 eventually dissolves all of the copper hydroxide and forms the Cu(NH3)4^+2 complex ammine. So I don't see how it goes to the left after the ammine is already formed.

Answer 2

I agree with Dr. Bob. I cant explain how you observed a left shift on the last.