[OhyesOhno69]

I am planning to make an experiment about chemical equilibrium and predicting the change on an equilibrium (eg. adding volume, or concentration or etc). are there any suggestions for this type of experiment? what should i consider? Thanks

[nj_bartel]

You could do an experiment where you add a common ion to make a ppt form, then consume that ion with something so that the ppt disappears.

[OhyesOhno69]

What is an example of that kind of experiment?

I got this in mind and I tried it...

CoCl42- + 6H2O <==> Co(H2O)62+ + 4Cl-
Blue                      Pink

its cobalt chloride with water.

I tried this using cobalt chloride hexahydrate crystals and mixing them with water. A pink solution is formed and I tried adding HCl (hydrochloric acid) 3 M into the solution so that the equilibrium shifts to the left but it's no good... the color of the solution just turned transparent.

What solution should I use then in order to shift the equilibrium to the left? Are there any alternative reactions should this one fails?